{"paper_id":"270a0570-2295-40ae-84f5-afbeff58cf67","body_text":"The generalist – specialist continuum for sharks based on stable isotope analysis of dental collagen | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The generalist – specialist continuum for sharks based on stable isotope analysis of dental collagen Alyssa D Valdez, Robin B. Trayler, Sho Tanaka, Sora Lee Kim This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-1631337/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract Dietary variability impacts food web dynamics and resource partitioning among individuals and species in a community. However, it is difficult to characterize the ecological niche of sharks, a mobile and long-lived predator. Stable isotope analysis allows the quantification of niche width since it incorporates both environmental and biological variation. Carbon isotope composition varies between marine productivity regimes while nitrogen isotope composition indicates trophic position, but baseline can vary with seasonal or regional shifts. We sampled dental collagen for stable isotope analysis. The conveyor-like growth of shark teeth provides a time series allowing for multiple measurements per individuals. We sampled 59 individuals from 11 species captured in 2005 at Suruga Bay, Japan (34°50'59.99\" N 138°32'59.99\" E). We estimated three ecological metrics based on stable isotope composition—standard ellipse area, convex hull area, and Pianka’s measure—which elucidated the extent of ecological variation and allowed comparisons among individuals and species. Our results show a significant positive correlation between dental collagen δ 15 N values and total length (r 2 = 0.23; p = 2⨉10 − 16 ), but individual variability had a low coefficient of determination. The variation in isotopic niche within and among individuals as well between species across all habitat types suggest that many species spanned the generalist – specialist continuum. Our findings indicate there are subtle ecological differences between species and among individuals; multiple measurements of carbon and nitrogen composition from multiple teeth series indicate variable ecological niches. Comparing patterns across habitats suggests sharks have complex food web dynamics with extensive individual- and species-level variation. Isotopic Niche Mesopredator Time Series Teeth Japan Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Predators play an important role in their ecosystems as biodiversity regulators with top-down pressures (Myers et al. 2007 ; Baum and Worm 2009 ) as well as ecological integrators of bottom up processes (Martinez del Rio et al. 2001 ; Bump et al. 2007 ). The ecological role of predators is linked to their network connectivity and phenotypic variation (Bolnick et al. 2007a ; Layman et al. 2007b ; Quevedo et al. 2009 ), which can be examined based on resource use. Two dimensions of resource use are diet variation and ecological niche. Diet variation is often classified with respect to generalist vs. specialist and ecological niche width, but there is a growing body of research that indicates generalist populations can be made up of specialist individuals (Bolnick et al. 2003 , 2007b ). The examination of population heterogeneity relative to individual variation is part of the niche variation hypothesis (Bolnick et al. 2007a ; Soule and Stewart 2009 ) and requires niche widths on the population and individual level. These metrics can be difficult to discern for long-lived and wide-ranging predators, such as sharks, which have seasonal, ontogenetic, and migratory changes in diet (Munroe et al., 2014 ). Niche width and individual variability are often investigated with stable isotope analysis that provides quantitative metrics to compare diet and trophic dynamics (Bortolotti et al., 2009; Newsome et al., 2009). Since there are isotopic differences among primary producers which are transferred to consumers, the relative abundance of 13 C/ 12 C or 15 N/ 14 N indicates energy flow through a food web (Koch, 2007; Layman et al., 2007). In marine ecosystems, stable carbon isotope compositions (δ 13 C) vary among regions with different productivity regimes (Goericke and Fry 1994), where variation within an individual or population indicate seasonal variation in one location or movement/migration between habitats regimes (i.e., Carlisle et al., 2012; Carlisle et al., 2015; Kim et al., 2012 ). Stable nitrogen isotope compositions (δ 15 N) are primarily used to determine an organism’s trophic position (see review of Layman et al., 2012). Enrichment of 15 N occurs in consumer tissues with the preferential excretion of 14 N in waste. Therefore, prey δ 15 N values increase and transfer to consumers with every trophic level (Koch 2007). Tissue incorporation rate also influences stable isotope composition. While most tissues incorporate dietary nutrients and maintain steady state, tissues with continuous incorporation and incremental growth capture a time series of diet (i.e., whiskers [Hückstädt et al., 2012], baleen [Ryan et al., 2013], and shark vertebrae [Kim et al., 2012 )]). These accretionary structures offer multiple measurements of diet and habitat preference that span seasonal and/or annual variability that can offer insight to differences within and between individuals or species. Shark teeth are continuously replaced in a conveyor belt-like formation, and analysis of dental collagen from multiple, sequential shark teeth offers a time series of ecological information related to diet and habitat (Shipley et al. 2021 a). Shark teeth are organized in rows perpendicular to the jaw with multiple series; the oldest teeth are in the functional position (i.e., series 1) while the most newly formed teeth are below the epithelial tissue (Smith et al., 2018; Smith et al., 2013). A single tooth represents a relatively short time (~ 45 days) but an entire of teeth row spans ~ 1 year (Zeichner et al. 2017 ). The advantage of multiple stable isotope measurements from a single tissue is the ability to discern seasonal or ontogenetic changes and individual variation (Kim et al., 2012 ; Newsome, Clementz, & Koch, 2010; Shipley et al., 2021 ) without need to recapture individuals or make assumptions to normalize data. For example, previous studies have sampled different tissues and rely on discrimination factors or incorporation rates as transfer functions to determine within individual variation (Matich et al., 2021 ). The analysis of multiple series within an individual’s jaw represents a timeframe of within individual variability that gives insight to seasonal changes in environmental conditions or movement patterns that can be compared to population or community level differences (Zeichner et al. 2017 ; Shipley et al. 2021 a). Here, we use stable isotope analysis to investigate trophic niche variation among 11 shark species within a community assemblage from Suruga Bay, Japan (Fig. 1 ), to broadly investigate niche dynamics and resource use withing and among species. First, we investigate how trophic niche space is partitioned among species within the community assemblage. Second, we seek to quantify niche space within individual sharks to better understand the dynamics of variation and competition among individuals of a single species. In particular, intra-species variation is often hard to characterize because it relies on multiple measurements from single individuals. We use stable isotope analysis of dental collagen from multiple teeth to address this problem and create a time series of data to capture temporal variation in dietary preference. Using these results, we quantify dietary variation using, convex hull and ellipse areas, to estimate niche size, and Pianka’s measure to investigate the degree of generalist and specialist behavior within shark species. We found extensive isotopic variation within individuals and species as well as little correspondence between species- and individual- level variation. In addition, stable isotope values from sharks within Suruga Bay suggest connectivity between the various habitats and similar variation in food web structure. Methods Study Area Suruga Bay is in the Shizuoka Prefecture of central Japan (Fig. 1 ) and where Shimizu Port, Yui Port, and Seno Umi are located. The Bay opens south to the Pacific Ocean with a connection via the warm current, Kuroshio, to the tropical ecosystems of the Philippine Sea. Surface water temperatures range between 19°C to 27°C in winter and summer, respectively, with a mean annual temperature of 23°C (Japan Meteorological Agency 2020 ; Toyoda et al. 2021 ). Several rivers discharge along the western margin of Suruga Bay into a large, flat seabed. However, at the Bay’s center, the Suruga Trough runs north and descends steeply to depths greater than 2000 meters (Iwata et al., 2005 ; Urakawa et al., 2001 ). These physical features affect Suruga Bay’s ecosystem due to seasonal changes in salinity (Tanaka et al., 2009 ), nutrient concentrations, and as large redox gradients (Urakawa et al. 2001 ). Suruga Bay has high biodiversity and 487 species of deep-water fishes have been identified within it (Shinohara et al., 2011 ). While deep-water sharks have been targeted by fisheries for squalene in their liver oil since World War II (Yano & Tanaka, 1984 ), many aspects of their ecology remain elusive. Sample collection Samples for this study were salvaged from fishery discard at Shimizu and Yui Ports (Fig. 1 ). The sharks were targeted or incidentally caught by fishing vessels in Suruga Bay during April - August 2005 with baited longline (500-800m), bottom gill nets (50-250m), trap set-net (0-50m) and bottom trawl net (150-300m). Species were identified and metadata (i.e., sex, total length, mass, maturity, etc.) was recorded at Port or in Tanaka’s laboratory during processing. Jaws were extracted and air dried before transporting to the United States where they were prepared for stable isotope analysis. Collected species include Dusky Shark Carcharhinus obscurus , Spinner Shark Carcharhinus brevipinna , Smooth Hammerhead Sphyrna zygaena , Japanese Topeshark Hemitriakis japanica , Starspotted Smooth-hound Mustelus manazo , Shortspine Spurdog Squalus mitsukurii , Rough Longnose Dogfish Deania hystricosa , Needle Dogfish Centrophorus acus (granulosus) , Roughskin Dogfish Centroscymnus owstomi , Sharpnose Sevengill Shark Heptranchias perlo , Japanese Velvet Dogfish Scymnodon ichiharai . Stable Isotope Analysis Sections of jaw from 11 species of sharks were separated into tooth series and labeled from T 1 -T i (where 1 = functional position and i = most recently formed tooth). Teeth were homogenized in a mortar and pestle, and demineralized using 1.0 mL of 4°C 0.5M HCl to isolate dental collagen. After demineralization, each sample was rinsed five times with deionized water and lyophilized before isotopic analysis. All samples were weighed to 0.3 ± 0.05 mg into tin capsules (3⨉5 mm, EA Consumables) and analyzed at the Stable Isotope Ecosystem Laboratory of UC Merced (SIELO) using a Costech 4010 Elemental Analyzer coupled with a Delta V Plus Continuous Flow Isotope Ratio Mass Spectrometer with a Conflo IV. Isotope ratios are presented in in δ notation as follows: $${\\delta }^{h}X=\\left(\\frac{{R}_{sample}}{{R}_{standard}}-1\\right)*1000$$ where X is the element, h is the heavy isotope and R is the ratio of the heavy to light isotope of element X (i.e., 13 C/ 12 C and 15 N/ 14 N). The standard used for δ 13 C is Vienna PeeDee Belemnite (VPDB) and for δ 15 N is AIR. Carbon and nitrogen isotope compositions were standardized to the international scale using USGS 40 (n = 15; δ 13 C = -26.4 ± 0.1‰; δ 15 N = 4.5 ± 0.2‰) and USGS 41a (n = 6; δ 13 C = 36.6 ± 0.1‰; δ 15 N = 47.4 ± 0.3‰) reference materials. We also analyzed aliquots of in-house acetanilide (n = 6; δ 13 C = -28.2 ± 0.1‰; δ 15 N = -0.4 ± 0.4‰) and homogenized squid tissue (n = 8; δ 13 C = -18.7 ± 0.1‰; δ 15 N = 11.7 ± 0.3‰) as quality control references. These results are indistinguishable from the SIELO long term average (squid: δ 13 C = -18.7 ± 0.1‰; δ 15 N = 11.8 ± 0.2‰; n = 155; acetanilide: δ 13 C = -28.3 ± 0.2‰; δ 15 N = -0.7 ± 0.3‰; n = 692). All uncertainties are reported as mean ± 1 standard deviation. All data were corrected for mass linearity and instrument drift. We re-analyzed 10% of our samples and found isotopic variation among re-runs to be within analytical error. Statistical Analysis Estimating Species Niche Size - We used the SIBER R package (Jackson et al., 2011 ) to estimate the ecological niche occupied by each species. SIBER calculates a variety of ecological metrics, including the corrected standard ellipse area (SEA c ), which we used to estimate the isotopic niche width for a species (see Layman et al., 2007). We also calculated the convex hull area (CHA) as a proxy for individual isotopic niche, but recognize this metric is sensitive to differences in sample size (Layman et al. 2007a ). Estimating Niche Overlap - We calculated Pianka’s measure (w) of niche overlap (Pianka 1974 ) to estimate niche partitioning within species. We used a version of the measure formulated for stable isotope data by Yeakel et al., ( 2011 ) $${\\omega }_{ij}= \\frac{\\sqrt[4]{\\left|{{\\Sigma }}_{i}{{\\Sigma }}_{j}\\right|}}{\\sqrt{|\\frac{1}{2}{{\\Sigma }}_{i}+{{\\Sigma }}_{j}|}} {e}^{-\\frac{1}{2}{({\\mu }_{i}-{\\mu }_{j})}^{\\text{'}}{({{\\Sigma }}_{i}-{{\\Sigma }}_{j})}^{-1}({\\mu }_{i}-{\\mu }_{j})}$$ Where µ i and µ j are vectors bivariate means of δ 13 C and δ 15 N, Σ i and Σ j are covariance matrices. See Yeakel et al., ( 2011 ) for further mathematical details. We calculated w ij for all individuals ( i ) relative to the pooled data for each species ( j ). In effect, this calculates how much each individual overlaps with its species population. Pianka’s measure varies from 0 to 1, where 0 is no niche overlap and 1 is perfectly overlapping niches which can indicate specialization or generalization (Kim et al., 2012 ; Yeakel et al., 2011 ). If there is a high degree of overlap, w ≈ 1 and indicates similar ecologies among individuals whereas less overlap (w ≈ 0) indicates more differentiation between individuals. Results We sampled 11 shark species (see §Sample Collection) from epipelagic, coastal, deep benthic, and abyssal habitats within Suruga Bay (habitat types determined based on Yano & Tanaka, 1983 ). Dental collagen was extracted and analyzed from 59 individuals (Table 1 ). Since individuals have multiple series of teeth, 255 samples were analyzed from these individuals with 3–5 series available from most individuals depending on the size of teeth and eruption pattern. Table 1 Summary of stable isotope data and ecological metrics. The mean δ 13 C and δ 15 N values as well as convex hull area and Pianka’s measure are reported with ± 1s. The corrected standard ellipse area is a species level metric. Species n δ 13 C (mean ± 1s) δ 15 N (mean ± 1s) Standard ellipse area (SEAc) Convex hull area (CHA) (mean ± 1s) Pianka (w) (mean ± 1s) Dusky Shark Carcharhinus obscurus 5 -12.8 ± 0.6 11.9 ± 1.0 2.0 0.5 ± 0.5 0.5 ± 0.1 Smooth Hammerhead Sphyrna zygaena 12 -14.4 ± 0.6 12.2 ± 0.8 1.5 0.5 ± 0.3 0.5 ± 0.2 Spinner Shark Carcharhinus brevipinna 2 -14.0 ± 0.6 11.8 ± 0.5 0.7 0.5 ± 0.2 0.7 ± 0.2 Japanese Topeshark emitriakis japanica 4 -13.5 ± 0.5 11.0 ± 0.6 0.9 0.3 ± 0.3 0.4 ± 0.2 Starspotted Smooth-hound Mustelus manazo 5 -13.3 ± 0.5 9.1 ± 0.9 1.4 1.2 ± 0.8 0.8 ± 0.2 Sharpnose Sevengill Shark Heptranchias perlo 8 -13.9 ± 1.2 12.6 ± 1.0 3.0 2.6 ± 1.9 0.7 ± 0.1 Shortspine Spurdog Squalus mitsukurii 3 -14.6 ± 0.6 10.4 ± 0.7 1.2 0.8 ± 0.7 0.8 ± 0.1 Japanese Velvet Dogfish Zameus ichiharai 2 -13.8 ± 0.5 14.0 ± 0.6 0.7 0.7 ± 0.1 0.9 ± 0.0 Needle Dogfish Centrophorus acus (granulosus) 8 -13.4 ± 1.0 13.4 ± 0.9 2.0 0.8 ± 0.4 0.5 ± 0.2 Rough Longnose Dogfish Deania hystricosa 6 -13.6 ± 0.6 12.5 ± 0.8 1.4 0.5 ± 0.3 0.5 ± 0.2 Roughskin Dogfish Centroscymnus owstomi 2 -14.2 ± 1.0 14.5 ± 0.5 1.2 0.5 ± 0.4 0.6 ± 0.3 Tooth samples for each species varied in δ 13 C and δ 15 N values. We monitored C:N ratio as an indicator of collagen quality (mean C:N = 2.9±0.3). The δ 13 C and δ 15 N values for all specimens’ dental collagen ranged from − 14.6 to -12.9‰ and 9.0 to 14.5‰, respectively, with mean values of -13.8±0.9‰ and 12.1±1.5‰, respectively (see Table 1 ; Fig. 2 ). The mean δ 13 C values for each habitat were as follows: epipelagic = -14.0±0.8‰, coastal = -13.4±0.5‰, deep benthic = -14.1±1.1‰, and abyssal = -13.6±0.8‰ (Fig. 2 ). The mean δ 15 N values for each habitat were as follows: epipelagic = 12.1±0.9‰, coastal = 9.9±1.2‰, deep benthic = 12.1±1.3‰, and abyssal = 13.3±1.0‰ (Fig. 2 ). The isotopic compositions for each habitat were normally distributed (Shapiro-Wilkes Test, Table 1 ) and significantly different for δ 13 C values (ANOVA, F 3,262 = 7.37, p = 0) and δ 15 N values (ANOVA, F 3,262 = 91.50, p = 0). Further, δ 13 C values were significantly different for the habitat comparisons of epipelagic-coastal, coastal-deep benthic, epipelagic-abyssal, and deep benthic-abyssal; the epipelagic-deep benthic and coastal-abyssal δ 13 C values were not significantly different (Table 2 ). A comparison among habitats for δ 15 N values yielded more statistically significant results; all habitat combinations were significantly different except epipelagic-deep benthic (Table 2 ). Table 2 Summary of statistical analyses by habitat. The species designated for each habitat are listed. We tested for normality with the Shipiro-Wilkes test (W and p value reported for δ 13 C and δ 15 N values), then performed pairwise comparisons with a Posthoc Tukey Honest Significant Differences (HSD) test. The Tukey HSD p-values for δ 13 C comparisons between habitats are above the “X” diagonal while δ 15 N comparisons are below. Habitat Species Shapiro-Wilkes Tukey Honest Significant Differences (depth range, color in figures) W, p Epipelagic (< 100m) Coastal (30-300m) Subarctic (100-400m) Abyssal (> 500m) Epipelagic (< 100m, oranges) Dusky Shark Smooth Hammerhead Spinner Shark δ 13 C: 0.974, 0.062 δ 15 N:0.993, 0.927 X p = 0.0020* p = 0.96 p = 0.019* Coastal (30-300m, greens) Japanese Topeshark Starspotted Smooth-hound δ 13 C: 0.962, 0.204 δ 15 N: 0.972, 0.433 p <<< 0.0001* X p = 0.0017* p = 0.57 Subarctic (100-400m, blues) Sharpnose Sevengill Shark Shortspine Spurdog δ 13 C: 0.977, 0.422 δ 15 N:0.979, 0.501 p = 1 p <<< 0.0001* X p = 0.016* Abyssal (> 500m, purples) Japanese Velvet Dogfish Needle Dogfish Rough Longnose Dogfish Roughskin Dogfish δ 13 C: 0.994, 0.955 δ 15 N: 0.988, 0.648 p <<< 0.0001* p <<< 0.0001* p <<< 0.0001* X Our results also demonstrate a significant relationship between dental collagen δ 15 N values and total length (p = 2⨉10 − 16 ), but individual variation resulted in a low coefficient of determination (r 2 = 0.23; Fig. 3 ). To quantify individual isotope niche width, we used convex hull area based on individual tooth series. The convex hull area for all individuals in our data set ranged from 0.7 to 4.5 (Fig. 4 , 5 B). Due to the varying number of individuals per species, we used standard ellipse area to determine species-level isotopic niche. The standard ellipse area for all species ranged from 0.6 (Spinner Shark) to 3.1 (Sharpnose Sevengill Shark) and species within each habitat (i.e., epipelagic, coastal, deep benthic, and abyssal) exhibited a range in standard ellipse area (Fig. 5 A). The Sharpnose Sevengill Shark had the largest standard ellipse area and individuals also had the greatest convex hull area. However, there are no trends in standard ellipse area and convex hull area among other species or habitats. We measured the extent of overlap among individuals within a species with Pianka’s measure (w). Our results ranged from 0.06 to 0.94 (Fig. 5 C), which encompasses almost the complete range of possible results (0 = no overlap and 1 = complete overlap). The mean w range (i.e., maximum w – minimum w) for eight species with N > 2, was 0.52 ± 0.17. Generally, species with fewer individuals exhibited smaller w range but even species with only two individuals indicated substantial variation (e.g., Roughskin Dogfish and Spinner Shark). Smooth Hammerheads had the largest range in w and highest number of individuals sampled (w range = 0.79, N = 12). Interestingly, the Starspotted Smooth-hound also had a large w range , but four individuals had w = 0.82–0.92 while one individual had w = 0.24. We did not observe a relationship between w and standard ellipse area or convex hull area. Discussion Ecological theory suggests generalists with large ecological niches are more likely to persist through stochastic processes. However, there is growing evidence that many generalist populations are comprised individual specialists (Bolnick et al., 2002 ). The stable isotope analysis of dental collagen from shark teeth provides multiple measurements per individual and can elucidate the extent of individual and population-level variation (Zeichner et al. 2017 ; Matich et al. 2021 ; Shipley et al. 2021 ). This study of the Suruga Bay shark community reveals a large variation in isotopic niche width. Generally, δ 15 N values increase with total length, suggesting correspondence of trophic level and size, but there is substantial variation within individuals (Fig. 3 ). Our results demonstrate that individuals within a species have different isotopic niche widths (Fig. 4 ), which does not necessarily correspond with the species-level niche width or overlap between individuals within a species (Fig. 5 ). The variation within individuals and among species indicates a continuum of generalists and specialists with a complex and diverse food web. Ecological Niche Width with Standard Ellipse Area (SEA c ) We estimated species-level isotopic niche using standard ellipse area (SEA c ) to reduce errors associated with sample size. While this metric accounts for sample size bias, we found that species with a greater total length diversity among individuals also had the largest standard ellipse area. This pattern reinforces that many sharks are gape-limited predators and undergo ontogenetic dietary shifts (Heupel et al., 2014 ), which is supported in this study by the significant relationship between total length and δ 15 N values (Fig. 3 ). The largest sharks in this study are the Needle Dogfish, which were near maximum adult size, but did not have the largest total niche width based on standard ellipse area (SEA c =1.96). A telemetric study of Needle Dogfish in Suruga Bay found bimodal depth preference (i.e., 300–400 and 580-620m) but little horizontal movement (Yano & Tanaka, 1986); the limited range of habitat is reflected in its relatively low SEA c . In contrast, the Sharpnose Sevengill shark had the largest length range (78.3–117.5 cm), which spans the size at maturity (95–105 cm for females and 70–85 cm in males) (Tanaka & Mizue, 1977 ), and largest standard ellipse area (SEA c =3.26). Previous studies found evidence of an ontogenetic shift in Sharpnose Sevengill diet (Barnett et al., 2012 ; Braccini, 2008 ), which likely accounts for the large isotopic niche exhibited in this study. The largest size distribution in this study was among Smooth hammerhead (58.4–106.1 cm) but the estimated isotopic niche width (SEA c =1.46) only reflects juveniles since the individuals sampled were substantially smaller than total length at maturity (250–260 cm; Miller, 2016 ). These comparisons of standard ellipse area among species imply the importance of size and ontogeny on the overall niche width sharks. We expect the actual isotopic niche to be larger for the species that we had limited representation, such as Spinner Shark, Rough Dogfish, and Japanese Velvet Dogfish. An assessment of population-level isotopic niche width is necessary to compare within vs. between individual variation, which is the greatest asset of using shark teeth as a substrate for stable isotope analysis. Individual Variability with Convex Hull Area (CHA) We used convex hull area to investigate how individuals parse the species-level isotopic niches. Using convex hull area as a metric for determining niche width is often criticized for biased niche geometry due to outlying data points and inconsistent sample sizes (Shipley and Matich 2020 ). However, convex hull areas are well suited to shark teeth because the same number of possible data points is controlled by the number of teeth available, and within a shark species the number of series is relatively constant (i.e., 3–5), so sample size bias is of less concern. Through teeth, we can compare convex hull areas of individuals within a species. Individuals that behave as generalists will have larger convex hull areas, whereas individual specialists will have smaller convex hull area. Our results indicate no relationship between individual- and species- level niche width as evidenced by convex hull area and standard ellipse areas, respectively, which suggests a continuum of ecological strategies spanning specialists to generalists in these adjacent shark communities within Suruga Bay. We chose to highlight the substantial individual-level variation within many species with convex hull area and compare to a species-level summary since this feature is uniquely captured in the stable isotope analysis of shark teeth. For example, individual Sharpnose Sevengill sharks have a convex hull area range of 0.2–5.65 (n = 8) while Smooth Hammerhead have a convex hull area range of 0.02–1.10 (n = 12). The differences in maximum convex hull area for these species indicate the extent of diet variation while the range demonstrates individual-level dietary differences. The range of convex hull area for each species loosely increases with number of individuals and given the wide range of individuals per species in this study, we are cautious to designate species as generalists or specialists with these estimates of convex hull area. Overlap among individuals within a species with Pianka’s Measure ( w ) A key feature of proposed quantitative comparisons of individual vs. population niche width is the extent of overlap (i.e., within vs. between individual component as outlined in Bolnick et al. 2002 ). We use Pianka’s measure to estimate this proportional overlap between individuals within a population while accounting for multivariate covariance (Pianka 1974 ; Yeakel et al. 2011 ). This metric complements convex hull area and standard ellipse area because it demonstrates the similarity among individuals within a population. In other words, Pianka’s measure can help distinguish if a generalist population is composed of specialist individuals behaving differently or individuals are also generalists. The most notable result of Pianka’s measure in this study is a broad range throughout both shark communities and within species that encompasses almost the entire possible range: 0.06–0.94 (Fig. 5 ). Some species featured in this study had small sample size (i.e., n ≤ 3) and therefore their range of Pianka’s measure was limited. While the correspondence of increasing δ 15 N values with total length supports some influence of gape-limited predation among sharks in these ecosystems (Fig. 3 ), most prominent in our results is the variation among individuals. For example, Needle Dogfish have the largest total length, highest δ 15 N values, and Pianka’s measure span 0.16–0.71, which suggests a range of foraging behaviors and/or preferences. We note the lack of correlation between Pianka’s measure and convex hull area throughout our dataset, which suggests the extent of individual diet variation is not tightly coupled to niche breadth for an individual or population. Comparing the ecology of sharks within Suruga Bay’s habitats Suruga Bay is an ideal location to explore patterns in ecological organization among predators given the proximity of multiple marine habitats. The spatial heterogeneity of this region coupled with the diverse shark community results in resource partitioning as evidenced by differences in stable isotope composition of sharks in the four habitats (Fig. 2 , Table 2 ). Further, the population vs. individual stable isotope variation for habitats within Suruga Bay resemble ecological models with patch formation and emergence of specialist competitors (Levin and Paine 1974 ). Epipelagic - We sampled juvenile Spinner Shark, Smooth Hammerhead, and Dusky Shark in the epipelagic zone of Suruga Bay. Based on δ 13 C and δ 15 N values, this habitat is well linked to the deep benthic habitat, but statistically different from the coastal and abyssal habitats. This dissociation between the epipelagic and coastal habitats is surprising since their proximity would suggest energy and resource exchange. However, the individuals featured in this study were all juveniles based on their total length (Compagno 2001 ). Further, it is likely that most individuals were young of the year given their total length compared to published the length at birth for each species (Joung et al., 2005 ; Choi, 2018 ; Rosa et al., 2017 ; Joung et al., 2015 ). The δ 15 N values of these juvenile sharks likely reflect a maternal signal given their age (Olin et al. 2011 ; Tamburin et al. 2019 ) and incorporation rate of dentin collagen (Zeichner et al. 2017 ). There is previous evidence for long distance migration in Spinner Shark (Rigby et al., 2020), Smooth Hammerhead (Santos and Coelho 2018 ), and Dusky Shark (Rogers et al., 2013 ). Further, studies from Korea and Taiwan on these species report the absence of the smallest size classes (Joung et al. 2005 , 2015 ; Choi 2018 ). It is possible that the stable isotope compositions in this study reflect adult diet in these other localities. The epipelagic habitat of Suruga Bay may serve as an important nursery for these species throughout the western North Pacific Ocean. Coastal - The two species from the coastal habitat, Japanese Topeshark and Starspotted Smooth-hound, are endemic to the western Pacific Basin and listed as endangered by the International Union for Conservation of Nature (Rigby et al., 2020; Walls et al., 2021 ). These two species exhibit a relatively narrow and overlapping range in δ 13 C values, which are distinct from all other habitats in Suruga Bay except the abyssal zone (Table 2 ). The Japanese Topeshark exhibits a smaller isotopic niche on the species and individual level based on standard ellipse and convex hull area (Fig. 5 ) but has higher δ 15 N values than the Starspotted Smooth-hound (Fig. 2 ). A previous study focused in the Seto Inland Sea, located southwest of Suruga Bay, found that Japanese Topeshark were only seasonally present and predominantly preyed on benthic cephalopod and fish whereas Starspotted Smooth-hound were present year around and fed on crustaceans and polycheates (Kamura and Hashimoto 2004 ). Starspotted Smooth-hound are known to have variable diets; a comparison of stomach contents between five localities found differences in prey preference (i.e., mantis shrimp, crab, hermit crab, shrimps, crustacean fragments, and polychaetes) with less diversity in larger individuals (Yamaguchi and Taniuchi 2000 ). In Suruga Bay, Starpotted Smooth-hound feed at a low trophic level (i.e., low δ 15 N values; Fig. 2 ) and the variation within and among individuals suggest it is a true generalist with variable individual diet (i.e., larger convex hull area; Fig. 4 ) and extensive overlap within the population with Pianka’s measure > 0.75 for four individuals (Fig. 5 C). The stable isotope composition of Japanese Topeshark in Suruga Bay reflects their diet of small fishes and cephalopods (Kamura and Hashimoto 2004 ), which are higher trophic prey than consumed by Starspotted Smooth-hound. In addition, Japanese Topeshark are caught in deeper waters (Yano & Kugai, 1993 ), which often have food webs enriched in 13 C and 15 N compared to epipelagic waters (Davison et al., 2013 ; Mintenbeck et al., 2007 ). These data contribute to growing evidence of the importance of sharks and fish in transferring energy and nutrients to deeper marine habitats (Carlisle et al., 2021 ; Davison et al., 2013 ; Trueman et al., 2014). Deep benthic - The deep benthic habitat of Suruga Bay is represented by the Shortspine Spurdog and Sharpnose Sevengill Shark. These two species differ in their distribution and stable isotope results provide new ecological insights. The Sharpnose Sevengill Shark is globally distributed in deep benthic habitat up to 1000m depth on the upper slope and has dietary data available from multiple regions (Barnett et al., 2012 ; Finucci et al., 2020). Previous studies determined Sharpnose Sevengill Shark diet to specialize on fish, crustaceans, and cephalopods in the Mediterranean, central Eastern Atlantic, and southern Australia (Braccini 2008 ; Barnett et al. 2012 ). However, in the context of the Suruga Bay shark assemblage, Sharpnose Sevengill Sharks have the largest isotopic niche on both the population and individual-level based on standard ellipse area and convex hull area, respectively, with a high degree of overlap among individuals (Fig. 2 , 4 , 5 ). This high degree of individual variation is also supported by two specimens analyzed for compound specific isotope analysis of amino acids; the δ 15 N values for the baseline are similar, but trophic variation is high (Fujiwara et al. 2021 ). In contrast, the Shortspine Spurdog has a limited distribution in deep benthic habitats of the Northwestern Pacific Ocean (Finucci et al., 2020; Ziadi-Künzli et al., 2020 ). The three specimens of Shortspine Spurdog in this study are immature females based on total length (Taniuchi and Tachikawa 1997 ) and their δ 15 N values suggests a lower trophic level diet than the Sharpnose Sevengill but similar to the Japanese Topeshark in the coastal habitat (Fig. 2 ). Further, the Shortspine Spurdog has a constrained isotopic niche based on dentin δ 13 C and δ 15 N values; this species has a smaller standard ellipse area and convex hull area than the Sharpnose Sevengill but also has high overlap with Pianka’s measure > 0.50 (Fig. 5 ). The species within the deep benthic habitat have different population- and individual-level isotopic niches, but individuals within each species have a similar feeding ecology and exhibit a high degree of overlap in their isotopic composition. Abyssal - The deepest habitat of Suruga Bay is its central trough where the Japanese Velvet Dogfish, Roughskin Dogfish, Rough Longnose Dogfish, and Needle dogfish inhabit (Yano & Tanaka, 1983 ). The specimens for each species represent a relatively narrow range of total length and are fully mature adults so there is minimal ontogenetic insight from their stable isotope composition. Generally, the diet of Squaliformes is known to be fish and squid, but more specific diet data is sparse given that many stomachs are emptied as specimens are brought to the surface (Yano & Tanaka, 1983 ). The δ 13 C and δ 15 N values from dentin collagen suggest there are differences in ecological niche among species as well as extensive individual-level variation within species. Our results indicate Needle Dogfish to occupy the largest isotopic niche as a species in the abyssal habitat with a standard ellipse area = 2.0, but this may also be a function of the relatively high sample size (N = 8; Table 1 ). The convex hull areas for individual Needle Dogfish spanned the largest range within this habitat and the extent of overlap among individuals varied widely (Table 1 , Fig. 5 ). Our study only included two specimens of Japanese Velvet Dogfish, but its diet is completely undescribed to date (Rigby et al. 2021 ). The Japanese Velvet Dogfish had elevated δ 15 N values, which is likely a result of feeding in the abyssal food web (Mintenbeck et al. 2015; Trueman et al., 2014) rather than high trophic level given that the specimens caught were < 100cm (Fig. 2 ). This species had the smallest isotopic niche and complete overlap in isotopic composition among individuals (Fig. 5 ). While these traits could be due to low sample size of Japanese Velvet Dogfish, we also only sampled two individual Roughskin Dogfish. These Roughskin Dogfish specimens produced similar results for species- and individual-level isotopic niche with their standard ellipse area and convex hull area, respectively (Fig. 5 ), but each specimen had different δ 13 C and δ 15 N distributions from dentin collagen and therefore diverged in their overlap. This variation among individuals aligns with a previous result from compound specific isotope analysis of amino acids that indicated similar baselines but different trophic level from two other specimens caught in Suruga Bay (Fujiwara et al. 2021 ). The final species caught in the abyssal habitat is the Rough Longnose Dogfish, which has reported distribution data but no published record of diet (Compagno 2001 ; Carpenter and Garilao 2021 ). The isotopic niche for Rough Longnose Dogfish are similar to the Roughskin Dogfish on the species- and individual-level as well as extent of overlap among individuals (Table 1 ; Fig. 5 ). However, the Rough Longnose Dogfish has the lowest mean δ 15 N values from dentin collagen of all species within the abyssal habitat, which could indicate foraging on prey from a shallower depth. Previous studies featuring deep water consumers and stable isotope analysis demonstrate the importance of diel-vertical migration, which transfers nutrients and links epipelagic, deep benthic, and abyssal marine habitats (Carlisle et al., 2021 ; Trueman et al., 2014). Although this study presents stable isotope compositions of consumers without prey data, the assessments individual vs. population variation provides an ecological context to evaluate resource use, ecological niche, and food web structure, which are substantial contributions for these species that are largely classified as “data deficient” and/or “vulnerable” (Froese and Pauly 2021 ). Conclusions Essentially all sharks are carnivorous and occupy upper trophic levels within marine ecosystems, but the more subtle ecological differences between species as well as within and among individuals remains elusive. Here, we examine ecological niche using stable isotope analysis from dentin collagen, which provides a more nuanced perspective of diet and habitat with multiple measurements of carbon and nitrogen isotope composition per individual. We compare within vs. between individual variation using a suite of computational metrics without assumptions related to tissue specific discrimination factors or incorporation rates. Our stable isotope results indicate substantial variation in δ 13 C and δ 15 N values for the shark community in adjacent habitats of Suruga Bay, Japan. A general trend in increasing δ 15 N values with total length (Fig. 3 ) suggest gape limited predation. In addition, we found a range of isotopic niche widths among species (e.g., standard ellipse area) and individuals (e.g., convex hull area), but no correlation between these ecological levels of organization. For example, Smooth Hammerhead and Needle Dogfish are generalist species with largest standard ellipse area, but individual convex hull areas vary in their size and distribution (Fig. 4 ), which indicates some niche partitioning. However, it is important to note the differences among individuals as evidenced by the distribution of Pianka’s measure (Fig. 5 ). Acknowledging this individual variation has ecological, evolutionary, and conservation implications to consider in future studies. Declarations Acknowledgements We thank A. Cruz Diaz and L. Jimenez who were instrumental in collecting stable isotope data; C. Cochran, M. Morris, and P. Valencia Landa for their assistance weighing samples; and L. Meyer for their ideas and feedback. We would also like to thank the Undergraduate Research Opportunities Center at UC Merced for supporting the students involved with this research during the Summer Undergraduate Research Institute and Fellowship. Funding: This research was funded in part by a National Science Foundation’s East Asia and Pacific Summer Institutes (NSF 0513060) and start-up funds from the University of California, Merced to SLK. Conflicts of interest/Competing: The authors have no conflicts of interest. Ethics approval: All applicable institutional and/or national guidelines for the care and use of animals were followed; in Japan, sampling from fishery discard does not require scientific collection permits or ethical approval in Japan. Consent to participate: NA Availability of data and material: Data available from the Dryad Digital Repository https://doi.org/ 10.6071/M34370 (Kim, Valdez, Trayler, & Tanaka, in review). Code availability: NA Authors' contributions: SLK and ST conceived the ideas and designed methodology; ST collected samples; ADV collected the data; ADV, RBT, and SLK analyzed the data; ADV, RBT and, SLK wrote the manuscript. All authors contributed critically to the drafts and gave final approval for publication. All authors also state they have no conflict of interest. References Barnett A, Braccini JM, Awruch CA, Ebert DA (2012) An overview on the role of Hexanchiformes in marine ecosystems: Biology, ecology and conservation status of a primitive order of modern sharks. J Fish Biol 80:966–990. doi: 10.1111/j.1095-8649.2012.03242.x Baum JK, Worm B (2009) Cascading top-down effects of changing oceanic predator abundances. J Anim Ecol 78:699–714. doi: 10.1111/j.1365-2656.2009.01531.x Bolnick DI, Yang LHY, Fordyce JA, Davis JM, Svanbäck R (2002) MEASURING INDIVIDUAL-LEVEL RESOURCE SPECIALIZATION. 83:2936–2941 Bolnick DI, Svanbäck R, Fordyce JA, Yang LH, Davis JM, Hulsey CD, Forister ML (2003) The ecology of individuals: Incidence and implications of individual specialization. Am Nat 161:1–28. doi: 10.1086/343878 Bolnick DI, Svanbäck R, Araújo MS, Persson L (2007a) Comparative support for the niche variation hypothesis that more generalized populations also are more heterogeneous. Proc Natl Acad Sci U S A 104:10075–10079. doi: 10.1073/pnas.0703743104 Bolnick DI, Svanbäck R, Araújo MS, Persson L (2007b) Comparative support for the niche variation hypothesis that more generalized populations also are more heterogeneous. Proc Natl Acad Sci U S A 104:10075–10079. doi: 10.1073/PNAS.0703743104 Braccini JM (2008) Feeding ecology of two high-order predators from south-eastern Australia: The coastal broadnose and the deepwater sharpnose sevengill sharks. Mar Ecol Prog Ser 371:273–284. doi: 10.3354/meps07684 Bump JK, Fox-Dobbs K, Bada JL, Koch PL, Peterson RO, Vucetich JA (2007) Stable isotopes, ecological integration and environmental change: Wolves record atmospheric carbon isotope trend better than tree rings. Proc R Soc B Biol Sci 274:2471–2480. doi: 10.1098/rspb.2007.0700 Carlisle AB, Allan EA, Kim SL, Meyer L, Port J, Scherrer S, O’Sullivan J (2021) Integrating multiple chemical tracers to elucidate the diet and habitat of Cookiecutter Sharks. Sci Rep 11:11809. doi: 10.1038/s41598-021-89903-z Carpenter KE, Garilao CV (2021) Deania hystricosa (Garman, 1906) Rough longnose dogfish. In: FishBase Choi Y (2018) A Pregnant Smooth Hammerhead Sphyrna zygaena, Collected in the Western Coastal Water, Korea. Korean J Ichthyol 30:167–169. doi: 10.35399/isk.30.3.6 Compagno LJV (2001) Sharks of the world: an annotated and illustrated catalogue of shark species known to date. Food \\& Agriculture Org Davison PC, Checkley DM, Koslow JA, Barlow J (2013) Carbon export mediated by mesopelagic fishes in the northeast Pacific Ocean. Prog Oceanogr 116:14–30. doi: 10.1016/J.POCEAN.2013.05.013 Finucci B, Barnett A, Bineesh KK, Cheok J, Cotton CF, Kulka DW, Neat FC, Rigby CL, Tanaka S, Walker TI (2020a) Heptranchias perlo, Sharpnose Sevengill Shark. In: The IUCN Red List of Threatened Species Finucci B, Cheok J, Cotton CF, Kulka DW, Neat FC, Pacoureau N, Rigby CL, Tanaka S, Walker TI (2020b) Squalus mitsukurii, Shortspine Spurdog Assessment. In: The IUCN Red List of Threatened Species Froese R, Pauly D (2021) Fishbase Fujiwara Y, Kawato M, Poulsen JY, Ida H, Chikaraishi Y, Ohkouchi N, Oguri K, Gotoh S, Ozawa G, Tanaka S, Miya M, Sado T, Kimoto K, Toyofuku T, Tsuchida S (2021) Discovery of a colossal slickhead (Alepocephaliformes: Alepocephalidae): an active-swimming top predator in the deep waters of Suruga Bay, Japan. Sci Rep 11:1–16. doi: 10.1038/s41598-020-80203-6 Heupel MR, Knip DM, Simpfendorfer CA, Dulvy NK (2014) Sizing up the ecological role of sharks as predators. Mar Ecol Prog Ser 495:291–298. doi: 10.3354/meps10597 Iwata T, Shinomura Y, Natori Y, Igarashi Y, Sohrin R, Suzuki Y (2005) Relationship between salinity and nutrients in the subsurface layer in the Suruga Bay. J Oceanogr 61:721–732. doi: 10.1007/s10872-005-0079-2 Jackson AL, Inger R, Parnell AC, Bearhop S (2011) Comparing isotopic niche widths among and within communities: SIBER - Stable Isotope Bayesian Ellipses in R. J Anim Ecol 80:595–602. doi: 10.1111/j.1365-2656.2011.01806.x Japan Meteorological Agency (2020) Climate Change Monitoring Report Joung SJ, Liao YY, Liu KM, Chen CT, Leu LC (2005) Age, growth, and reproduction of the spinner shark, Carcharhinus brevipinna, in the northeastern waters of Taiwan. Zool Stud 44:102–110 Joung SJ, Chen JH, Chin CP, Liu KM (2015) Age and growth of the dusky shark, Carcharhinus obscurus, in the Western North Pacific Ocean. Terr Atmos Ocean Sci 26:153–160. doi: 10.3319/TAO.2014.10.15.01(Oc) Kamura S, Hashimoto H (2004) The food habits of four species of triakid sharks, Triakis scyllium, Hemitriakis japanica, Mustelus griseus and Mustelus manazo, in the central Seto Inland Sea, Japan. Fish Sci 70:1019–1035. doi: 10.1111/j.1444-2906.2004.00902.x Kim SLSL, Del Rio CMCM, Casper D, Koch PLPL (2012) Isotopic incorporation rates for shark tissues from a long-Term captive feeding study. J Exp Biol 215:2495–2500. doi: 10.1242/jeb.070656 Layman CA, Albrey Arrington D, Montaña CG, Montaña M, Post DM (2007a)CAN STABLE ISOTOPE RATIOS PROVIDE FOR COMMUNITY-WIDE MEASURES OF TROPHIC STRUCTURE? Layman CA, Quattrochi JP, Peyer CM, Allgeier JE (2007b) Niche width collapse in a resilient top predator following ecosystem fragmentation. Ecol Lett 10:937–944. doi: 10.1111/j.1461-0248.2007.01087.x Levin SA, Paine RT (1974) Disturbance, patch formation, and community structure. Proc Natl Acad Sci U S A 71:2744–2747. doi: 10.1073/pnas.71.7.2744 Martinez del Rio C, Dugelby B, Foreman D, Miller B, Noss R, Phillips M (2001) The importance of large carnivores to healthy ecosystems. Endanger Species Updat 18:202–210 Matich P, Bizzarro JJ, Shipley ON (2021) Are stable isotope ratios suitable for describing niche partitioning and individual specialization? Ecol Appl 31:1–8. doi: 10.1002/eap.2392 Miller MH (2016) Endangered Species Act status review report: smooth hammerhead shark. Sphyrna zygaena) Mintenbeck K, Jacob U, Knust R, Arntz WE, Brey T (2007) Depth-dependence in stable isotope ratio δ15N of benthic POM consumers: The role of particle dynamics and organism trophic guild. Deep Sea Res Part I Oceanogr Res Pap 54:1015–1023. doi: 10.1016/J.DSR.2007.03.005 Munroe SEM, Simpfendorfer CA, Heupel MR (2014) Defining shark ecological specialisation: Concepts, context, and examples. Rev Fish Biol Fish 24:317–331 Myers RA, Baum JK, Shepherd TD, Powers SP, Peterson CH (2007) Cascading effects of the loss of apex predatory sharks from a coastal ocean. Sci (80-) 315:1846–1850. doi: 10.1126/science.1138657 Olin JA, Hussey NE, Fritts M, Heupel MR, Simpfendorfer CA, Poulakis GR, Fisk AT (2011) Maternal meddling in neonatal sharks: Implications for interpreting stable isotopes in young animals. Rapid Commun Mass Spectrom 25:1008–1016. doi: 10.1002/rcm.4946 Pianka ER (1974) Niche overlap and diffuse competition. Proc Natl Acad Sci U S A 71:2141–2145. doi: 10.1073/pnas.71.5.2141 Quevedo M, Svanbäck R, Eklöav P (2009) Intrapopulation niche partitioning in a generalist predator limits food web connectivity. Ecology 90:2263–2274. doi: 10.1890/07-1580.1 Rigby CL, Bin Ali A, Bineesh KK, Chen X, Derrick D, Dharmadi, Ebert DA, Fahmi, Fernando D, Gautama DA, Haque AB, Ho H, Hsu H, Krajangdara T, Maung A, Vo VQ, Sianipar A, Tanay D, Utzurrum JAT, Yuneni RR, Zhang J (2020a) Mustelus manazo, Starspotted Smooth-hound. In: The IUCN Red List of Threatened Species Rigby CL, Carlson J, Smart JJ, Pacoureau N, Herman K, Derrick D, Brown E (2020b) Spinner Shark Carcharhinus brevipinna. The IUCN Red List of Threatened Species Rigby CL, Walls RHL, Derrick D, Dyldin YV, Herman K, Ishihara H, Jeong C-H, Semba Y, Tanaka S, Volvenko IV, Yamaguchi A (2021) Scymnodon ichiharai Japanese Velvet Dogfish. 8235 Rogers PJ, Huveneers C, Goldsworthy SD, Mitchell JG, Seuront L (2013) Broad-scale movements and pelagic habitat of the dusky shark Carcharhinus obscurus off Southern Australia determined using pop-up satellite archival tags. Fish Oceanogr 22:102–112. doi: 10.1111/fog.12009 Rosa D, Coelho R, Fernandez-Carvalho J, Santos MN (2017) Age and growth of the smooth hammerhead, Sphyrna zygaena, in the Atlantic Ocean: comparison with other hammerhead species. Mar Biol Res 13:300–313. doi: 10.1080/17451000.2016.1267366 Santos CC, Coelho R (2018) Migrations and habitat use of the smooth hammerhead shark (sphyrna zygaena) in the atlantic ocean. PLoS ONE 13:1–17. doi: 10.1371/journal.pone.0198664 Shinohara G, Shirai SM, Nazarkin MV, Yabe M (2011) Preliminary List of the Deep-sea Fishes of the Sea of Japan. Bull Natl Museum Nat Sccience 37:35–62 Shipley ON, Matich P (2020) Studying animal niches using bulk stable isotope ratios: an updated synthesis. Oecologia 193:27–51. doi: 10.1007/s00442-020-04654-4 Shipley ON, Henkes GA, Gelsleichter J, Morgan CR, Schneider EV, Talwar BS, Frisk MG (2021) Shark tooth collagen stable isotopes (δ15N and δ13C) as ecological proxies. J Anim Ecol 90:2188–2201. doi: 10.1111/1365-2656.13518 Soule M, Stewart BR (2009) The American Society of Naturalists The \" Niche-Variation \" Hypothesis: A Test and Alternatives. 104:85–97 Tamburin E, Kim SL, Elorriaga-Verplancken FR, Madigan DJ, Hoyos-Padilla M, Sánchez-González A, Hernández-Herrera A, Castillo-Geniz JL, Godinez-Padilla CJ, Galván-Magaña F (2019) Isotopic niche and resource sharing among young sharks (carcharodon carcharias and isurus oxyrinchus) in baja California, Mexico. Mar Ecol Prog Ser 613:107–124. doi: 10.3354/meps12884 Tanaka K, Michida Y, Komatsu T, Ishigami K (2009) Spreading of river water in Suruga Bay. J Oceanogr 65:165–177. doi: 10.1007/s10872-009-0016-x Tanaka S, Mizue K (1977) Studies on Sharks-XI: Reproduction in Female Heptranchias perlo. Bull Fac Fish Nagasaki Univ 42:1–9 Taniuchi T, Tachikawa H (1997) Geographical variation in age and growth of Squalus mitsukurii (Elasmobranchii: Squalidae) in north Pacific. In: Proceedings of 5th Indo-Pacific Fish Conference, Nouméa. pp 321–328 Toyoda T, Sakamoto K, Usui N, Hirose N, Tanaka K, Katsumata T, Takahashi D, Niki M, Kutsuwada K, Miyama T, Nakano H, Urakawa LS, Komatsu KK, Kawakami Y, Yamanaka G (2021) Surface-Layer Circulations in Suruga Bay Induced by Intrusions of Kuroshio Branch Water. Front Mar Sci 8:1243. doi: 10.3389/FMARS.2021.721500/BIBTEX Trueman CN, Johnston G, O’Hea B, MacKenzie KM (2014a) Trophic interactions of fish communities at midwater depths enhance long-term carbon storage and benthic production on continental slopes. Proc R Soc B Biol Sci 281:1–10. doi: 10.1098/rspb.2014.0669 Trueman CN, Johnston G, O’hea B, Mackenzie KM (2014b) Trophic interactions of fish communities at midwater depths enhance long-term carbon storage and benthic production on continental slopes. Proc R Soc B Biol Sci 281:1–10. doi: 10.1098/rspb.2014.0669 Urakawa H, Yoshida T, Nishimura M, Ohwada K (2001) Characterization of microbial communities in marine surface sediments by terminal-restriction fragment length polymorphism (T-RFLP) analysis and quinone profiling. Mar Ecol Prog Ser. doi: 10.3354/meps220047 Walls RHL, Rigby CL, Derrick D, Dyldin YV, Herman K, Ishihara H, Jeong C-H, Semba Y, Tanaka S, Volvenko IV, Yamaguchi A (2021) Hemitriakis japanica, Japanese Topeshark. In: The IUCN Red List of Threatened Species Yamaguchi A, Taniuchi T (2000) Food variations and ontogenetic dietary shift of the starspotted-dogfish Mustelus manazo at five locations in Japan and Taiwan. Fish Sci 66:1039–1048. doi: 10.1046/j.1444-2906.2000.00166.x Yano K, Kugai K (1993) Deep-sea chondrichthyans collected from the waters around the Okinawa Islands:. results of catch analysis of bottom longlines Yano K, Tanaka S (1983) Biological Studies on Squaloid Sharks from Suruga Bay, Japan. In: Proceedings 2nd North Pacific Aquaculture Symposium. Tokyo and Shimizu, Japan, pp 407–414 Yano K, Tanaka S (1984) Some Biological Aspects of the Deep Sea Squaloid Shark Centroscymnus from Suruga Bay, Japan. Nippon SUISAN GAKKAISHI. 10.2331/suisan.50.249 Yano K and ST (1986) A telemetric study on the movements of the deep sea squaloid shark, Centrophorus acus. Indo-Pacific Fish Biology: Proceed. Sec. Inter. Conf. on Indo-Pacific Fishes. Ichthyological Society of Japan, Tokyo, pp 372–380 Yeakel JD, Novak M, Guimarães PR, Dominy NJ, Koch PL, Ward EJ, Moore JW, Semmens BX (2011) Merging resource availability with isotope mixing models: The role of neutral interaction assumptions. PLoS ONE 6:1–8. doi: 10.1371/journal.pone.0022015 Zeichner SS, Colman AS, Koch PL, Polo-Silva C, Galván-Magaña F, Kim SL (2017) Discrimination factors and incorporation rates for organic matrix in shark teeth based on a captive feeding study. Physiol Biochem Zool 90:257–272. doi: 10.1086/689192 Ziadi-Künzli F, Soliman T, Imai H, Sakurai M, Maeda K, Tachihara K (2020) Re-evaluation of deep-sea dogfishes (genus Squalus) in Japan using phylogenetic inference. Deep Res Part I Oceanogr Res Pap 160:103261. doi: 10.1016/j.dsr.2020.103261 Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 10 May, 2022 Reviewers invited by journal 09 May, 2022 Editor assigned by journal 07 May, 2022 First submitted to journal 06 May, 2022 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {\"props\":{\"pageProps\":{\"initialData\":{\"identity\":\"rs-1631337\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":false,\"archivedVersions\":[],\"articleType\":\"Research Article\",\"associatedPublications\":[],\"authors\":[{\"id\":104649071,\"identity\":\"9c79c923-d266-4ed4-92e7-983729092989\",\"order_by\":0,\"name\":\"Alyssa D Valdez\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"University of California Riverside\",\"correspondingAuthor\":false,\"submittingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Alyssa\",\"middleName\":\"D\",\"lastName\":\"Valdez\",\"suffix\":\"\"},{\"id\":104649072,\"identity\":\"abd147a3-121d-473c-a5b1-d6e28a6009a5\",\"order_by\":1,\"name\":\"Robin B. Trayler\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"University of California Merced\",\"correspondingAuthor\":false,\"submittingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Robin\",\"middleName\":\"B.\",\"lastName\":\"Trayler\",\"suffix\":\"\"},{\"id\":104649073,\"identity\":\"ef995739-dd1a-4fb1-8e3c-d3da2700b6d0\",\"order_by\":2,\"name\":\"Sho Tanaka\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Tokai University - Shimizu Campus: Tokai Daigaku - Shimizu Campus\",\"correspondingAuthor\":false,\"submittingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Sho\",\"middleName\":\"\",\"lastName\":\"Tanaka\",\"suffix\":\"\"},{\"id\":104649074,\"identity\":\"69dc553f-1ba3-4333-a269-bbc3832af18b\",\"order_by\":3,\"name\":\"Sora Lee Kim\",\"email\":\"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA5klEQVRIiWNgGAWjYDACHsYGxg8VEnIwPmMDA4MBQS3MEmdsjEnRAsS8bWmJDURrke853LpB4szh9A3HTyc+rqixkW1gb94mgU+LwdnGthsFFYdzN5zJ3Wx45liacQPPsTL8WvgZ224AbcndcIN3m2Rjw+HEBokcM7xa5PuBWnjbDqcb3ODd/rOx4X9ig/wb/FoYQA4Dej8BqGUbY2PDAaAtPPi1GJw52HYbGMiGM4F+kWw4lmzcxpNWbIHXYT3pz24Co1Ke7/jZjR8bauxk+9kPb7yB12EYgI005aNgFIyCUTAKsAEAiutS69rSdOsAAAAASUVORK5CYII=\",\"orcid\":\"https://orcid.org/0000-0002-4900-3101\",\"institution\":\"University of California\",\"correspondingAuthor\":true,\"submittingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Sora\",\"middleName\":\"Lee\",\"lastName\":\"Kim\",\"suffix\":\"\"}],\"badges\":[],\"createdAt\":\"2022-05-06 23:18:00\",\"currentVersionCode\":1,\"declarations\":\"\",\"doi\":\"10.21203/rs.3.rs-1631337/v1\",\"doiUrl\":\"https://doi.org/10.21203/rs.3.rs-1631337/v1\",\"draftVersion\":[],\"editorialEvents\":[],\"editorialNote\":\"\",\"failedWorkflow\":false,\"files\":[{\"id\":21401295,\"identity\":\"50356586-7c81-4d3b-ad88-8fb426a9b872\",\"added_by\":\"auto\",\"created_at\":\"2022-05-12 16:13:03\",\"extension\":\"png\",\"order_by\":1,\"title\":\"Figure 1\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":83594,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eA) The sharks in this study were caught within Suruga Bay on the southern coast of Honshu Island, Japan (indicated with a red box). B) This nearshore marine habitat has variable depth gradients and includes a central trough that reaches depths of 2500m (bathymetry contours by 100m, darker colors are deeper). Opportunistic samples were taken for stable isotope analysis from the discard at either Shimizu or Yui Ports. One area targeted by fisheries within Suruga Bay is Seno Umi, shown as a grey shaded region on the western side of Suruga Bay.\\u0026nbsp;\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Fig1.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-1631337/v1/9008f588e5b50e5036fa2d3c.png\"},{\"id\":21400862,\"identity\":\"0695a77e-17dd-4858-a48b-c824eaf6c4a7\",\"added_by\":\"auto\",\"created_at\":\"2022-05-12 16:08:03\",\"extension\":\"png\",\"order_by\":2,\"title\":\"Figure 2\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":74401,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eThe carbon and nitrogen isotope composition of dental collagen from sharks caught in Suruga Bay categorized by preferred depth/habitat. Warmer to cooler colors indicating preferred depth/habitat as follows: A) epipelagic (\\u0026lt;100m) in oranges, B) coastal (30-300m) in greens, C) deep benthic (100-400m) in blues, and D) abyssal (\\u0026gt;500m) in purples. Each color represents a single species with data for individual tooth series as well as standard ellipse areas (SEA\\u003csub\\u003ec\\u003c/sub\\u003e). The collated data for all individuals and species in each habitat are shown as marginal rug plots.\\u0026nbsp;\\u0026nbsp;\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Fig2.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-1631337/v1/2bd673a5320f0efcab881de2.png\"},{\"id\":21400860,\"identity\":\"9d51c34e-c9cb-4275-8c17-bd09c08824f6\",\"added_by\":\"auto\",\"created_at\":\"2022-05-12 16:08:03\",\"extension\":\"png\",\"order_by\":3,\"title\":\"Figure 3\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":26163,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eNitrogen isotope composition vs. total length across all species. There is an overall positive relationship, but the multiple d\\u003csup\\u003e15\\u003c/sup\\u003eN values from multiple tooth series per specimen indicate the extent of temporal variation in diet and habitat. Species colors reflect those in Figure 2 with oranges representing epipelagic (\\u0026lt;100m), greens representing coastal (30-300m), blue representing deep benthic (100-400m), and purples representing abyssal (\\u0026gt;500m) habitats.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Fig3.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-1631337/v1/eb49dd53f6fea221905b2d00.png\"},{\"id\":21400864,\"identity\":\"fd65d1df-65a3-45de-a363-baa3ae384f8b\",\"added_by\":\"auto\",\"created_at\":\"2022-05-12 16:08:03\",\"extension\":\"png\",\"order_by\":4,\"title\":\"Figure 4\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":38138,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eThe extent of individual variation is shown as the convex hull area (CHA), a polygon based on the isotopic composition of dental collagen from multiple series of an individual. Shark species featured in this study are shown in each inset with colors corresponding to those in Figure 2. The preferred habitat and depth with color schematic are as follows: A – C) epipelagic (\\u0026lt;100m) in oranges; D – E) coastal (30-300m) in greens; F \\u0026amp; G) deep benthic (100-400m) in blues; H – K) abyssal (\\u0026gt;500m) in purples.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Fig4.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-1631337/v1/6b1bc6ae2a9c05ac4a07e429.png\"},{\"id\":21400861,\"identity\":\"ea429738-a944-4773-a40f-bc4ba5f06d52\",\"added_by\":\"auto\",\"created_at\":\"2022-05-12 16:08:03\",\"extension\":\"png\",\"order_by\":5,\"title\":\"Figure 5\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":40006,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eA) The isotopic variation among shark species in Suruga Bay is captured with the standard ellipse area (SEA\\u003csub\\u003ec\\u003c/sub\\u003e). B) Multiple d\\u003csup\\u003e13\\u003c/sup\\u003eC and d\\u003csup\\u003e15\\u003c/sup\\u003eN values per individual from tooth series provides a measure of individual variation as Convex Hull Area (see Fig. 4). C) A comparison of individual vs. population similarity within each species is based on Pianka’s measure, w, where 0 = no overlap and 1 = complete overlap. There is a gradient from generalists to specialists based on these metrics within this shark assemblage that span all habitats (epipelagic [\\u0026lt;100m] in oranges, coastal [30-300m] in greens, deep benthic [100-400m] in blues, and abyssal [\\u0026gt;500m] in purples).\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Fig5.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-1631337/v1/610ea177d712d9816d1c3950.png\"},{\"id\":21401326,\"identity\":\"f7d69af7-b0ce-48f4-a5b6-16135a349ad1\",\"added_by\":\"auto\",\"created_at\":\"2022-05-12 16:13:06\",\"extension\":\"pdf\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"manuscript-pdf\",\"size\":429819,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"manuscript.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-1631337/v1/87a5a33a-768d-4d20-8993-ecadc6f891ba.pdf\"}],\"financialInterests\":\"\",\"formattedTitle\":\"The generalist – specialist continuum for sharks based on stable isotope analysis of dental collagen\",\"fulltext\":[{\"header\":\"Introduction\",\"content\":\"\\u003cp\\u003ePredators play an important role in their ecosystems as biodiversity regulators with top-down pressures (Myers et al. \\u003cspan citationid=\\\"CR34\\\" class=\\\"CitationRef\\\"\\u003e2007\\u003c/span\\u003e; Baum and Worm \\u003cspan citationid=\\\"CR2\\\" class=\\\"CitationRef\\\"\\u003e2009\\u003c/span\\u003e) as well as ecological integrators of bottom up processes (Martinez del Rio et al. \\u003cspan citationid=\\\"CR29\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e; Bump et al. \\u003cspan citationid=\\\"CR8\\\" class=\\\"CitationRef\\\"\\u003e2007\\u003c/span\\u003e). The ecological role of predators is linked to their network connectivity and phenotypic variation (Bolnick et al. \\u003cspan citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e2007a\\u003c/span\\u003e; Layman et al. \\u003cspan citationid=\\\"CR27\\\" class=\\\"CitationRef\\\"\\u003e2007b\\u003c/span\\u003e; Quevedo et al. \\u003cspan citationid=\\\"CR37\\\" class=\\\"CitationRef\\\"\\u003e2009\\u003c/span\\u003e), which can be examined based on resource use. Two dimensions of resource use are diet variation and ecological niche. Diet variation is often classified with respect to generalist vs. specialist and ecological niche width, but there is a growing body of research that indicates generalist populations can be made up of specialist individuals (Bolnick et al. \\u003cspan citationid=\\\"CR4\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR6\\\" class=\\\"CitationRef\\\"\\u003e2007b\\u003c/span\\u003e). The examination of population heterogeneity relative to individual variation is part of the niche variation hypothesis (Bolnick et al. \\u003cspan citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e2007a\\u003c/span\\u003e; Soule and Stewart \\u003cspan citationid=\\\"CR47\\\" class=\\\"CitationRef\\\"\\u003e2009\\u003c/span\\u003e) and requires niche widths on the population and individual level. These metrics can be difficult to discern for long-lived and wide-ranging predators, such as sharks, which have seasonal, ontogenetic, and migratory changes in diet (Munroe et al., \\u003cspan citationid=\\\"CR33\\\" class=\\\"CitationRef\\\"\\u003e2014\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eNiche width and individual variability are often investigated with stable isotope analysis that provides quantitative metrics to compare diet and trophic dynamics (Bortolotti et al., 2009; Newsome et al., 2009). Since there are isotopic differences among primary producers which are transferred to consumers, the relative abundance of \\u003csup\\u003e13\\u003c/sup\\u003eC/\\u003csup\\u003e12\\u003c/sup\\u003eC or \\u003csup\\u003e15\\u003c/sup\\u003eN/\\u003csup\\u003e14\\u003c/sup\\u003eN indicates energy flow through a food web (Koch, 2007; Layman et al., 2007). In marine ecosystems, stable carbon isotope compositions (δ\\u003csup\\u003e13\\u003c/sup\\u003eC) vary among regions with different productivity regimes (Goericke and Fry 1994), where variation within an individual or population indicate seasonal variation in one location or movement/migration between habitats regimes (i.e., Carlisle et al., 2012; Carlisle et al., 2015; Kim et al., \\u003cspan citationid=\\\"CR25\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e). Stable nitrogen isotope compositions (δ\\u003csup\\u003e15\\u003c/sup\\u003eN) are primarily used to determine an organism\\u0026rsquo;s trophic position (see review of Layman et al., 2012). Enrichment of \\u003csup\\u003e15\\u003c/sup\\u003eN occurs in consumer tissues with the preferential excretion of \\u003csup\\u003e14\\u003c/sup\\u003eN in waste. Therefore, prey δ\\u003csup\\u003e15\\u003c/sup\\u003eN values increase and transfer to consumers with every trophic level (Koch 2007). Tissue incorporation rate also influences stable isotope composition. While most tissues incorporate dietary nutrients and maintain steady state, tissues with continuous incorporation and incremental growth capture a time series of diet (i.e., whiskers [H\\u0026uuml;ckst\\u0026auml;dt et al., 2012], baleen [Ryan et al., 2013], and shark vertebrae [Kim et al., \\u003cspan citationid=\\\"CR25\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e)]). These accretionary structures offer multiple measurements of diet and habitat preference that span seasonal and/or annual variability that can offer insight to differences within and between individuals or species.\\u003c/p\\u003e \\u003cp\\u003eShark teeth are continuously replaced in a conveyor belt-like formation, and analysis of dental collagen from multiple, sequential shark teeth offers a time series of ecological information related to diet and habitat (Shipley et al. \\u003cspan citationid=\\\"CR46\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003ea). Shark teeth are organized in rows perpendicular to the jaw with multiple series; the oldest teeth are in the functional position (i.e., series 1) while the most newly formed teeth are below the epithelial tissue (Smith et al., 2018; Smith et al., 2013). A single tooth represents a relatively short time (~\\u0026thinsp;45 days) but an entire of teeth row spans\\u0026thinsp;~\\u0026thinsp;1 year (Zeichner et al. \\u003cspan citationid=\\\"CR63\\\" class=\\\"CitationRef\\\"\\u003e2017\\u003c/span\\u003e). The advantage of multiple stable isotope measurements from a single tissue is the ability to discern seasonal or ontogenetic changes and individual variation (Kim et al., \\u003cspan citationid=\\\"CR25\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e; Newsome, Clementz, \\u0026amp; Koch, 2010; Shipley et al., \\u003cspan citationid=\\\"CR46\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e) without need to recapture individuals or make assumptions to normalize data. For example, previous studies have sampled different tissues and rely on discrimination factors or incorporation rates as transfer functions to determine within individual variation (Matich et al., \\u003cspan citationid=\\\"CR30\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e). The analysis of multiple series within an individual\\u0026rsquo;s jaw represents a timeframe of within individual variability that gives insight to seasonal changes in environmental conditions or movement patterns that can be compared to population or community level differences (Zeichner et al. \\u003cspan citationid=\\\"CR63\\\" class=\\\"CitationRef\\\"\\u003e2017\\u003c/span\\u003e; Shipley et al. \\u003cspan citationid=\\\"CR46\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003ea).\\u003c/p\\u003e \\u003cp\\u003eHere, we use stable isotope analysis to investigate trophic niche variation among 11 shark species within a community assemblage from Suruga Bay, Japan (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e), to broadly investigate niche dynamics and resource use withing and among species. First, we investigate how trophic niche space is partitioned among species within the community assemblage. Second, we seek to quantify niche space within individual sharks to better understand the dynamics of variation and competition among individuals of a single species. In particular, intra-species variation is often hard to characterize because it relies on multiple measurements from single individuals. We use stable isotope analysis of dental collagen from multiple teeth to address this problem and create a time series of data to capture temporal variation in dietary preference. Using these results, we quantify dietary variation using, convex hull and ellipse areas, to estimate niche size, and Pianka\\u0026rsquo;s measure to investigate the degree of generalist and specialist behavior within shark species. We found extensive isotopic variation within individuals and species as well as little correspondence between species- and individual- level variation. In addition, stable isotope values from sharks within Suruga Bay suggest connectivity between the various habitats and similar variation in food web structure.\\u003c/p\\u003e\"},{\"header\":\"Methods\",\"content\":\" \\u003cdiv id=\\\"Sec2\\\" class=\\\"Section2\\\"\\u003e \\u003cdiv id=\\\"Sec3\\\" class=\\\"Section3\\\"\\u003e \\u003ch2\\u003eStudy Area\\u003c/h2\\u003e \\u003cp\\u003eSuruga Bay is in the Shizuoka Prefecture of central Japan (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e) and where Shimizu Port, Yui Port, and Seno Umi are located. The Bay opens south to the Pacific Ocean with a connection via the warm current, Kuroshio, to the tropical ecosystems of the Philippine Sea. Surface water temperatures range between 19\\u0026deg;C to 27\\u0026deg;C in winter and summer, respectively, with a mean annual temperature of 23\\u0026deg;C (Japan Meteorological Agency \\u003cspan citationid=\\\"CR21\\\" class=\\\"CitationRef\\\"\\u003e2020\\u003c/span\\u003e; Toyoda et al. \\u003cspan citationid=\\\"CR52\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e). Several rivers discharge along the western margin of Suruga Bay into a large, flat seabed. However, at the Bay\\u0026rsquo;s center, the Suruga Trough runs north and descends steeply to depths greater than 2000 meters (Iwata et al., \\u003cspan citationid=\\\"CR19\\\" class=\\\"CitationRef\\\"\\u003e2005\\u003c/span\\u003e; Urakawa et al., \\u003cspan citationid=\\\"CR55\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e). These physical features affect Suruga Bay\\u0026rsquo;s ecosystem due to seasonal changes in salinity (Tanaka et al., \\u003cspan citationid=\\\"CR49\\\" class=\\\"CitationRef\\\"\\u003e2009\\u003c/span\\u003e), nutrient concentrations, and as large redox gradients (Urakawa et al. \\u003cspan citationid=\\\"CR55\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e). Suruga Bay has high biodiversity and 487 species of deep-water fishes have been identified within it (Shinohara et al., \\u003cspan citationid=\\\"CR44\\\" class=\\\"CitationRef\\\"\\u003e2011\\u003c/span\\u003e). While deep-water sharks have been targeted by fisheries for squalene in their liver oil since World War II (Yano \\u0026amp; Tanaka, \\u003cspan citationid=\\\"CR60\\\" class=\\\"CitationRef\\\"\\u003e1984\\u003c/span\\u003e), many aspects of their ecology remain elusive.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec4\\\" class=\\\"Section3\\\"\\u003e \\u003ch2\\u003eSample collection\\u003c/h2\\u003e \\u003cp\\u003eSamples for this study were salvaged from fishery discard at Shimizu and Yui Ports (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e). The sharks were targeted or incidentally caught by fishing vessels in Suruga Bay during April - August 2005 with baited longline (500-800m), bottom gill nets (50-250m), trap set-net (0-50m) and bottom trawl net (150-300m). Species were identified and metadata (i.e., sex, total length, mass, maturity, etc.) was recorded at Port or in Tanaka\\u0026rsquo;s laboratory during processing. Jaws were extracted and air dried before transporting to the United States where they were prepared for stable isotope analysis. Collected species include Dusky Shark \\u003cem\\u003eCarcharhinus obscurus\\u003c/em\\u003e, Spinner Shark \\u003cem\\u003eCarcharhinus brevipinna\\u003c/em\\u003e, Smooth Hammerhead \\u003cem\\u003eSphyrna zygaena\\u003c/em\\u003e, Japanese Topeshark \\u003cem\\u003eHemitriakis japanica\\u003c/em\\u003e, Starspotted Smooth-hound \\u003cem\\u003eMustelus manazo\\u003c/em\\u003e, Shortspine Spurdog \\u003cem\\u003eSqualus mitsukurii\\u003c/em\\u003e, Rough Longnose Dogfish \\u003cem\\u003eDeania hystricosa\\u003c/em\\u003e, Needle Dogfish \\u003cem\\u003eCentrophorus acus (granulosus)\\u003c/em\\u003e, Roughskin Dogfish \\u003cem\\u003eCentroscymnus owstomi\\u003c/em\\u003e, Sharpnose Sevengill Shark \\u003cem\\u003eHeptranchias perlo\\u003c/em\\u003e, Japanese Velvet Dogfish \\u003cem\\u003eScymnodon ichiharai\\u003c/em\\u003e.\\u003c/p\\u003e \\u003cdiv id=\\\"Sec5\\\" class=\\\"Section4\\\"\\u003e \\u003ch2\\u003eStable Isotope Analysis\\u003c/h2\\u003e \\u003cp\\u003eSections of jaw from 11 species of sharks were separated into tooth series and labeled from T\\u003csub\\u003e1\\u003c/sub\\u003e-T\\u003csub\\u003ei\\u003c/sub\\u003e (where 1\\u0026thinsp;=\\u0026thinsp;functional position and \\u003cem\\u003ei\\u003c/em\\u003e\\u0026thinsp;=\\u0026thinsp;most recently formed tooth). Teeth were homogenized in a mortar and pestle, and demineralized using 1.0 mL of 4\\u0026deg;C 0.5M HCl to isolate dental collagen. After demineralization, each sample was rinsed five times with deionized water and lyophilized before isotopic analysis.\\u003c/p\\u003e \\u003cp\\u003eAll samples were weighed to 0.3\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.05 mg into tin capsules (3⨉5 mm, EA Consumables) and analyzed at the Stable Isotope Ecosystem Laboratory of UC Merced (SIELO) using a Costech 4010 Elemental Analyzer coupled with a Delta V Plus Continuous Flow Isotope Ratio Mass Spectrometer with a Conflo IV. Isotope ratios are presented in in δ notation as follows:\\u003cdiv id=\\\"Equa\\\" class=\\\"Equation\\\"\\u003e\\u003cdiv format=\\\"TEX\\\" class=\\\"mathdisplay\\\" id=\\\"FileID_Equa\\\" name=\\\"EquationSource\\\"\\u003e\\n$${\\\\delta }^{h}X=\\\\left(\\\\frac{{R}_{sample}}{{R}_{standard}}-1\\\\right)*1000$$\\u003c/div\\u003e\\u003c/div\\u003e\\u003c/p\\u003e \\u003cp\\u003ewhere X is the element, h is the heavy isotope and R is the ratio of the heavy to light isotope of element X (i.e., \\u003csup\\u003e13\\u003c/sup\\u003eC/\\u003csup\\u003e12\\u003c/sup\\u003eC and \\u003csup\\u003e15\\u003c/sup\\u003eN/\\u003csup\\u003e14\\u003c/sup\\u003eN). The standard used for δ\\u003csup\\u003e13\\u003c/sup\\u003eC is Vienna PeeDee Belemnite (VPDB) and for δ\\u003csup\\u003e15\\u003c/sup\\u003eN is AIR. Carbon and nitrogen isotope compositions were standardized to the international scale using USGS 40 (n\\u0026thinsp;=\\u0026thinsp;15; δ\\u003csup\\u003e13\\u003c/sup\\u003eC = -26.4\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.1\\u0026permil;; δ\\u003csup\\u003e15\\u003c/sup\\u003eN = 4.5\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.2\\u0026permil;) and USGS 41a (n\\u0026thinsp;=\\u0026thinsp;6; δ\\u003csup\\u003e13\\u003c/sup\\u003eC = 36.6\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.1\\u0026permil;; δ\\u003csup\\u003e15\\u003c/sup\\u003eN = 47.4\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.3\\u0026permil;) reference materials. We also analyzed aliquots of in-house acetanilide (n\\u0026thinsp;=\\u0026thinsp;6; δ\\u003csup\\u003e13\\u003c/sup\\u003eC = -28.2\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.1\\u0026permil;; δ\\u003csup\\u003e15\\u003c/sup\\u003eN = -0.4\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.4\\u0026permil;) and homogenized squid tissue (n\\u0026thinsp;=\\u0026thinsp;8; δ\\u003csup\\u003e13\\u003c/sup\\u003eC = -18.7\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.1\\u0026permil;; δ\\u003csup\\u003e15\\u003c/sup\\u003eN = 11.7\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.3\\u0026permil;) as quality control references. These results are indistinguishable from the SIELO long term average (squid: δ\\u003csup\\u003e13\\u003c/sup\\u003eC = -18.7\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.1\\u0026permil;; δ\\u003csup\\u003e15\\u003c/sup\\u003eN = 11.8\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.2\\u0026permil;; n\\u0026thinsp;=\\u0026thinsp;155; acetanilide: δ\\u003csup\\u003e13\\u003c/sup\\u003eC = -28.3\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.2\\u0026permil;; δ\\u003csup\\u003e15\\u003c/sup\\u003eN = -0.7\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.3\\u0026permil;; n\\u0026thinsp;=\\u0026thinsp;692). All uncertainties are reported as mean\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1 standard deviation. All data were corrected for mass linearity and instrument drift. We re-analyzed 10% of our samples and found isotopic variation among re-runs to be within analytical error.\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec6\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eStatistical Analysis\\u003c/h2\\u003e \\u003cp\\u003e\\u003cspan type=\\\"Underline\\\" class=\\\"Underline\\\" name=\\\"Emphasis\\\"\\u003eEstimating Species Niche Size\\u003c/span\\u003e - We used the SIBER R package (Jackson et al., \\u003cspan citationid=\\\"CR20\\\" class=\\\"CitationRef\\\"\\u003e2011\\u003c/span\\u003e) to estimate the ecological niche occupied by each species. SIBER calculates a variety of ecological metrics, including the corrected standard ellipse area (SEA\\u003csub\\u003ec\\u003c/sub\\u003e), which we used to estimate the isotopic niche width for a species (see Layman et al., 2007). We also calculated the convex hull area (CHA) as a proxy for individual isotopic niche, but recognize this metric is sensitive to differences in sample size (Layman et al. \\u003cspan citationid=\\\"CR26\\\" class=\\\"CitationRef\\\"\\u003e2007a\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003e \\u003cspan type=\\\"Underline\\\" class=\\\"Underline\\\" name=\\\"Emphasis\\\"\\u003eEstimating Niche Overlap\\u003c/span\\u003e - We calculated Pianka\\u0026rsquo;s measure (w) of niche overlap (Pianka \\u003cspan citationid=\\\"CR36\\\" class=\\\"CitationRef\\\"\\u003e1974\\u003c/span\\u003e) to estimate niche partitioning within species. We used a version of the measure formulated for stable isotope data by Yeakel et al., (\\u003cspan citationid=\\\"CR62\\\" class=\\\"CitationRef\\\"\\u003e2011\\u003c/span\\u003e)\\u003cdiv id=\\\"Equb\\\" class=\\\"Equation\\\"\\u003e\\u003cdiv format=\\\"TEX\\\" class=\\\"mathdisplay\\\" id=\\\"FileID_Equb\\\" name=\\\"EquationSource\\\"\\u003e\\n$${\\\\omega }_{ij}= \\\\frac{\\\\sqrt[4]{\\\\left|{{\\\\Sigma }}_{i}{{\\\\Sigma }}_{j}\\\\right|}}{\\\\sqrt{|\\\\frac{1}{2}{{\\\\Sigma }}_{i}+{{\\\\Sigma }}_{j}|}} {e}^{-\\\\frac{1}{2}{({\\\\mu }_{i}-{\\\\mu }_{j})}^{\\\\text{\\u0026#039;}}{({{\\\\Sigma }}_{i}-{{\\\\Sigma }}_{j})}^{-1}({\\\\mu }_{i}-{\\\\mu }_{j})}$$\\u003c/div\\u003e\\u003c/div\\u003e\\u003c/p\\u003e \\u003cp\\u003eWhere \\u003cem\\u003e\\u0026micro;\\u003c/em\\u003e\\u003csub\\u003e\\u003cem\\u003ei\\u003c/em\\u003e\\u003c/sub\\u003e and \\u003cem\\u003e\\u0026micro;\\u003c/em\\u003e\\u003csub\\u003e\\u003cem\\u003ej\\u003c/em\\u003e\\u003c/sub\\u003e are vectors bivariate means of δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e15\\u003c/sup\\u003eN, \\u003cem\\u003eΣ\\u003c/em\\u003e\\u003csub\\u003e\\u003cem\\u003ei\\u003c/em\\u003e\\u003c/sub\\u003e and \\u003cem\\u003eΣ\\u003c/em\\u003e\\u003csub\\u003e\\u003cem\\u003ej\\u003c/em\\u003e\\u003c/sub\\u003e are covariance matrices. See Yeakel et al., (\\u003cspan citationid=\\\"CR62\\\" class=\\\"CitationRef\\\"\\u003e2011\\u003c/span\\u003e) for further mathematical details. We calculated w\\u003csub\\u003eij\\u003c/sub\\u003e for all individuals (\\u003cem\\u003ei\\u003c/em\\u003e) relative to the pooled data for each species (\\u003cem\\u003ej\\u003c/em\\u003e). In effect, this calculates how much each individual overlaps with its species population. Pianka\\u0026rsquo;s measure varies from 0 to 1, where 0 is no niche overlap and 1 is perfectly overlapping niches which can indicate specialization or generalization (Kim et al., \\u003cspan citationid=\\\"CR25\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e; Yeakel et al., \\u003cspan citationid=\\\"CR62\\\" class=\\\"CitationRef\\\"\\u003e2011\\u003c/span\\u003e). If there is a high degree of overlap, w \\u0026asymp; 1 and indicates similar ecologies among individuals whereas less overlap (w \\u0026asymp; 0) indicates more differentiation between individuals.\\u003c/p\\u003e \\u003c/div\\u003e\"},{\"header\":\"Results\",\"content\":\"\\u003cp\\u003eWe sampled 11 shark species (see \\u0026sect;Sample Collection) from epipelagic, coastal, deep benthic, and abyssal habitats within Suruga Bay (habitat types determined based on Yano \\u0026amp; Tanaka, \\u003cspan citationid=\\\"CR59\\\" class=\\\"CitationRef\\\"\\u003e1983\\u003c/span\\u003e). Dental collagen was extracted and analyzed from 59 individuals (Table\\u0026nbsp;\\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e). Since individuals have multiple series of teeth, 255 samples were analyzed from these individuals with 3\\u0026ndash;5 series available from most individuals depending on the size of teeth and eruption pattern.\\u003c/p\\u003e \\u003cp\\u003e \\u003cdiv class=\\\"gridtable\\\"\\u003e\\u003ctable float=\\\"Yes\\\" id=\\\"Tab1\\\" border=\\\"1\\\"\\u003e \\u003ccaption language=\\\"En\\\"\\u003e \\u003cdiv class=\\\"CaptionNumber\\\"\\u003eTable 1\\u003c/div\\u003e \\u003cdiv class=\\\"CaptionContent\\\"\\u003e \\u003cp\\u003eSummary of stable isotope data and ecological metrics. The mean δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e15\\u003c/sup\\u003eN values as well as convex hull area and Pianka\\u0026rsquo;s measure are reported with \\u0026plusmn;\\u0026thinsp;1s. The corrected standard ellipse area is a species level metric.\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/caption\\u003e \\u003ccolgroup cols=\\\"11\\\"\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c1\\\" colnum=\\\"1\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c2\\\" colnum=\\\"2\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c3\\\" colnum=\\\"3\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c4\\\" colnum=\\\"4\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c5\\\" colnum=\\\"5\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c6\\\" colnum=\\\"6\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c7\\\" colnum=\\\"7\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c8\\\" colnum=\\\"8\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c9\\\" colnum=\\\"9\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c10\\\" colnum=\\\"10\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c11\\\" colnum=\\\"11\\\"\\u003e\\u003c/div\\u003e \\u003cthead\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eSpecies\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003en\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colspan=\\\"2\\\" nameend=\\\"c4\\\" namest=\\\"c3\\\"\\u003e \\u003cp\\u003eδ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003c/p\\u003e \\u003cp\\u003e(mean\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1s)\\u003c/p\\u003e\\u003c/th\\u003e \\u003cth align=\\\"left\\\" colspan=\\\"2\\\" nameend=\\\"c6\\\" namest=\\\"c5\\\"\\u003e \\u003cp\\u003eδ\\u003csup\\u003e15\\u003c/sup\\u003eN\\u003c/p\\u003e \\u003cp\\u003e(mean\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1s)\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003eStandard ellipse area (SEAc)\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colspan=\\\"2\\\" nameend=\\\"c9\\\" namest=\\\"c8\\\"\\u003e \\u003cp\\u003eConvex hull area (CHA)\\u003c/p\\u003e \\u003cp\\u003e(mean\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1s)\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colspan=\\\"2\\\" nameend=\\\"c11\\\" namest=\\\"c10\\\"\\u003e \\u003cp\\u003ePianka (w)\\u003c/p\\u003e \\u003cp\\u003e(mean\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1s)\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003c/thead\\u003e \\u003ctbody\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eDusky Shark\\u003c/p\\u003e \\u003cp\\u003e\\u003cem\\u003eCarcharhinus obscurus\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e-12.8\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.6\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e11.9\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;1.0\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e2.0\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c10\\\"\\u003e \\u003cp\\u003e0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c11\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.1\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eSmooth Hammerhead\\u003c/p\\u003e \\u003cp\\u003e\\u003cem\\u003eSphyrna zygaena\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e12\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e-14.4\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.6\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e12.2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.8\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e1.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.3\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c10\\\"\\u003e \\u003cp\\u003e0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c11\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.2\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eSpinner Shark\\u003c/p\\u003e \\u003cp\\u003e\\u003cem\\u003eCarcharhinus brevipinna\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e-14.0\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.6\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e11.8\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e0.7\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c10\\\"\\u003e \\u003cp\\u003e0.7\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c11\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.2\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eJapanese Topeshark\\u003c/p\\u003e \\u003cp\\u003e\\u003cem\\u003eemitriakis japanica\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e4\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e-13.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e11.0\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.6\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e0.9\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e0.3\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.3\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c10\\\"\\u003e \\u003cp\\u003e0.4\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c11\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.2\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eStarspotted Smooth-hound\\u003c/p\\u003e \\u003cp\\u003e\\u003cem\\u003eMustelus manazo\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e-13.3\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e9.1\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.9\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e1.4\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e1.2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.8\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c10\\\"\\u003e \\u003cp\\u003e0.8\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c11\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.2\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eSharpnose Sevengill Shark\\u003c/p\\u003e \\u003cp\\u003e\\u003cem\\u003eHeptranchias perlo\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e8\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e-13.9\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;1.2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e12.6\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;1.0\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e3.0\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e2.6\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;1.9\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c10\\\"\\u003e \\u003cp\\u003e0.7\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c11\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.1\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eShortspine Spurdog\\u003c/p\\u003e \\u003cp\\u003e\\u003cem\\u003eSqualus mitsukurii\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e3\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e-14.6\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.6\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e10.4\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.7\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e1.2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e0.8\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.7\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c10\\\"\\u003e \\u003cp\\u003e0.8\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c11\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.1\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eJapanese Velvet Dogfish\\u003c/p\\u003e \\u003cp\\u003e\\u003cem\\u003eZameus ichiharai\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e-13.8\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e14.0\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.6\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e0.7\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e0.7\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.1\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c10\\\"\\u003e \\u003cp\\u003e0.9\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c11\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.0\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eNeedle Dogfish\\u003c/p\\u003e \\u003cp\\u003e\\u003cem\\u003eCentrophorus acus (granulosus)\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e8\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e-13.4\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;1.0\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e13.4\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.9\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e2.0\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e0.8\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.4\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c10\\\"\\u003e \\u003cp\\u003e0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c11\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.2\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eRough Longnose Dogfish\\u003c/p\\u003e \\u003cp\\u003e\\u003cem\\u003eDeania hystricosa\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e6\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e-13.6\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.6\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e12.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.8\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e1.4\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.3\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c10\\\"\\u003e \\u003cp\\u003e0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c11\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.2\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eRoughskin Dogfish\\u003c/p\\u003e \\u003cp\\u003e\\u003cem\\u003eCentroscymnus owstomi\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e-14.2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;1.0\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e14.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e1.2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.4\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c10\\\"\\u003e \\u003cp\\u003e0.6\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c11\\\"\\u003e \\u003cp\\u003e\\u0026plusmn;\\u0026thinsp;0.3\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003c/tbody\\u003e \\u003c/colgroup\\u003e \\u003c/table\\u003e\\u003c/div\\u003e \\u003c/p\\u003e \\u003cp\\u003eTooth samples for each species varied in δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e15\\u003c/sup\\u003eN values. We monitored C:N ratio as an indicator of collagen quality (mean C:N\\u0026thinsp;=\\u0026thinsp;2.9\\u0026plusmn;0.3). The δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e15\\u003c/sup\\u003eN values for all specimens\\u0026rsquo; dental collagen ranged from \\u0026minus;\\u0026thinsp;14.6 to -12.9\\u0026permil; and 9.0 to 14.5\\u0026permil;, respectively, with mean values of -13.8\\u0026plusmn;0.9\\u0026permil; and 12.1\\u0026plusmn;1.5\\u0026permil;, respectively (see Table\\u0026nbsp;\\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e; Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e). The mean δ\\u003csup\\u003e13\\u003c/sup\\u003eC values for each habitat were as follows: epipelagic = -14.0\\u0026plusmn;0.8\\u0026permil;, coastal = -13.4\\u0026plusmn;0.5\\u0026permil;, deep benthic = -14.1\\u0026plusmn;1.1\\u0026permil;, and abyssal = -13.6\\u0026plusmn;0.8\\u0026permil; (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e). The mean δ\\u003csup\\u003e15\\u003c/sup\\u003eN values for each habitat were as follows: epipelagic\\u0026thinsp;=\\u0026thinsp;12.1\\u0026plusmn;0.9\\u0026permil;, coastal\\u0026thinsp;=\\u0026thinsp;9.9\\u0026plusmn;1.2\\u0026permil;, deep benthic\\u0026thinsp;=\\u0026thinsp;12.1\\u0026plusmn;1.3\\u0026permil;, and abyssal\\u0026thinsp;=\\u0026thinsp;13.3\\u0026plusmn;1.0\\u0026permil; (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e). The isotopic compositions for each habitat were normally distributed (Shapiro-Wilkes Test, Table\\u0026nbsp;\\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e) and significantly different for δ\\u003csup\\u003e13\\u003c/sup\\u003eC values (ANOVA, F\\u003csub\\u003e3,262\\u003c/sub\\u003e = 7.37, p\\u0026thinsp;=\\u0026thinsp;0) and δ\\u003csup\\u003e15\\u003c/sup\\u003eN values (ANOVA, F\\u003csub\\u003e3,262\\u003c/sub\\u003e = 91.50, p\\u0026thinsp;=\\u0026thinsp;0). Further, δ\\u003csup\\u003e13\\u003c/sup\\u003eC values were significantly different for the habitat comparisons of epipelagic-coastal, coastal-deep benthic, epipelagic-abyssal, and deep benthic-abyssal; the epipelagic-deep benthic and coastal-abyssal δ\\u003csup\\u003e13\\u003c/sup\\u003eC values were not significantly different (Table\\u0026nbsp;\\u003cspan refid=\\\"Tab2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e). A comparison among habitats for δ\\u003csup\\u003e15\\u003c/sup\\u003eN values yielded more statistically significant results; all habitat combinations were significantly different except epipelagic-deep benthic (Table\\u0026nbsp;\\u003cspan refid=\\\"Tab2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003e \\u003cdiv class=\\\"gridtable\\\"\\u003e\\u003ctable float=\\\"Yes\\\" id=\\\"Tab2\\\" border=\\\"1\\\"\\u003e \\u003ccaption language=\\\"En\\\"\\u003e \\u003cdiv class=\\\"CaptionNumber\\\"\\u003eTable 2\\u003c/div\\u003e \\u003cdiv class=\\\"CaptionContent\\\"\\u003e \\u003cp\\u003eSummary of statistical analyses by habitat. The species designated for each habitat are listed. We tested for normality with the Shipiro-Wilkes test (W and p value reported for δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e15\\u003c/sup\\u003eN values), then performed pairwise comparisons with a Posthoc Tukey Honest Significant Differences (HSD) test. The Tukey HSD p-values for δ\\u003csup\\u003e13\\u003c/sup\\u003eC comparisons between habitats are above the \\u0026ldquo;X\\u0026rdquo; diagonal while δ\\u003csup\\u003e15\\u003c/sup\\u003eN comparisons are below.\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/caption\\u003e \\u003ccolgroup cols=\\\"7\\\"\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c1\\\" colnum=\\\"1\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c2\\\" colnum=\\\"2\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c3\\\" colnum=\\\"3\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c4\\\" colnum=\\\"4\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c5\\\" colnum=\\\"5\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c6\\\" colnum=\\\"6\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c7\\\" colnum=\\\"7\\\"\\u003e\\u003c/div\\u003e \\u003cthead\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eHabitat\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\" morerows=\\\"1\\\" rowspan=\\\"2\\\"\\u003e \\u003cp\\u003eSpecies\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eShapiro-Wilkes\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colspan=\\\"4\\\" nameend=\\\"c7\\\" namest=\\\"c4\\\"\\u003e \\u003cp\\u003eTukey Honest Significant Differences\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e(depth range,\\u003c/p\\u003e \\u003cp\\u003ecolor in figures)\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eW, p\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003eEpipelagic\\u003c/p\\u003e \\u003cp\\u003e(\\u0026lt;\\u0026thinsp;100m)\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003eCoastal\\u003c/p\\u003e \\u003cp\\u003e(30-300m)\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003eSubarctic\\u003c/p\\u003e \\u003cp\\u003e(100-400m)\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003eAbyssal\\u003c/p\\u003e \\u003cp\\u003e(\\u0026gt;\\u0026thinsp;500m)\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003c/thead\\u003e \\u003ctbody\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eEpipelagic\\u003c/p\\u003e \\u003cp\\u003e(\\u0026lt;\\u0026thinsp;100m, oranges)\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eDusky Shark\\u003c/p\\u003e \\u003cp\\u003eSmooth Hammerhead\\u003c/p\\u003e \\u003cp\\u003eSpinner Shark\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eδ\\u003csup\\u003e13\\u003c/sup\\u003eC: 0.974, 0.062\\u003c/p\\u003e \\u003cp\\u003eδ\\u003csup\\u003e15\\u003c/sup\\u003eN:0.993, 0.927\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003eX\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003ep\\u0026thinsp;=\\u0026thinsp;0.0020*\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003ep\\u0026thinsp;=\\u0026thinsp;0.96\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003ep\\u0026thinsp;=\\u0026thinsp;0.019*\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eCoastal\\u003c/p\\u003e \\u003cp\\u003e(30-300m, greens)\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eJapanese Topeshark\\u003c/p\\u003e \\u003cp\\u003eStarspotted Smooth-hound\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eδ\\u003csup\\u003e13\\u003c/sup\\u003eC: 0.962, 0.204\\u003c/p\\u003e \\u003cp\\u003eδ\\u003csup\\u003e15\\u003c/sup\\u003eN: 0.972, 0.433\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003ep \\u0026lt;\\u0026lt;\\u0026lt; 0.0001*\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003eX\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003ep\\u0026thinsp;=\\u0026thinsp;0.0017*\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003ep\\u0026thinsp;=\\u0026thinsp;0.57\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eSubarctic\\u003c/p\\u003e \\u003cp\\u003e(100-400m, blues)\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eSharpnose Sevengill Shark\\u003c/p\\u003e \\u003cp\\u003eShortspine Spurdog\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eδ\\u003csup\\u003e13\\u003c/sup\\u003eC: 0.977, 0.422\\u003c/p\\u003e \\u003cp\\u003eδ\\u003csup\\u003e15\\u003c/sup\\u003eN:0.979, 0.501\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003ep\\u0026thinsp;=\\u0026thinsp;1\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003ep \\u0026lt;\\u0026lt;\\u0026lt; 0.0001*\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003eX\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003ep\\u0026thinsp;=\\u0026thinsp;0.016*\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eAbyssal\\u003c/p\\u003e \\u003cp\\u003e(\\u0026gt;\\u0026thinsp;500m, purples)\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eJapanese Velvet Dogfish\\u003c/p\\u003e \\u003cp\\u003eNeedle Dogfish\\u003c/p\\u003e \\u003cp\\u003eRough Longnose Dogfish\\u003c/p\\u003e \\u003cp\\u003eRoughskin Dogfish\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eδ\\u003csup\\u003e13\\u003c/sup\\u003eC: 0.994, 0.955\\u003c/p\\u003e \\u003cp\\u003eδ\\u003csup\\u003e15\\u003c/sup\\u003eN: 0.988, 0.648\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003ep \\u0026lt;\\u0026lt;\\u0026lt; 0.0001*\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003ep \\u0026lt;\\u0026lt;\\u0026lt; 0.0001*\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003ep \\u0026lt;\\u0026lt;\\u0026lt; 0.0001*\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003eX\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003c/tbody\\u003e \\u003c/colgroup\\u003e \\u003c/table\\u003e\\u003c/div\\u003e \\u003c/p\\u003e \\u003cp\\u003eOur results also demonstrate a significant relationship between dental collagen δ\\u003csup\\u003e15\\u003c/sup\\u003eN values and total length (p\\u0026thinsp;=\\u0026thinsp;2⨉10\\u003csup\\u003e\\u0026minus;\\u0026thinsp;16\\u003c/sup\\u003e), but individual variation resulted in a low coefficient of determination (r\\u003csup\\u003e2\\u003c/sup\\u003e\\u0026thinsp;=\\u0026thinsp;0.23; Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e). To quantify individual isotope niche width, we used convex hull area based on individual tooth series. The convex hull area for all individuals in our data set ranged from 0.7 to 4.5 (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig4\\\" class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003e, \\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003eB). Due to the varying number of individuals per species, we used standard ellipse area to determine species-level isotopic niche. The standard ellipse area for all species ranged from 0.6 (Spinner Shark) to 3.1 (Sharpnose Sevengill Shark) and species within each habitat (i.e., epipelagic, coastal, deep benthic, and abyssal) exhibited a range in standard ellipse area (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003eA). The Sharpnose Sevengill Shark had the largest standard ellipse area and individuals also had the greatest convex hull area. However, there are no trends in standard ellipse area and convex hull area among other species or habitats.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003eWe measured the extent of overlap among individuals within a species with Pianka\\u0026rsquo;s measure (w). Our results ranged from 0.06 to 0.94 (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003eC), which encompasses almost the complete range of possible results (0\\u0026thinsp;=\\u0026thinsp;no overlap and 1\\u0026thinsp;=\\u0026thinsp;complete overlap). The mean w\\u003csub\\u003erange\\u003c/sub\\u003e (i.e., maximum w \\u0026ndash; minimum w) for eight species with N\\u0026thinsp;\\u0026gt;\\u0026thinsp;2, was 0.52\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.17. Generally, species with fewer individuals exhibited smaller w\\u003csub\\u003erange\\u003c/sub\\u003e but even species with only two individuals indicated substantial variation (e.g., Roughskin Dogfish and Spinner Shark). Smooth Hammerheads had the largest range in w and highest number of individuals sampled (w\\u003csub\\u003erange\\u003c/sub\\u003e = 0.79, N\\u0026thinsp;=\\u0026thinsp;12). Interestingly, the Starspotted Smooth-hound also had a large w\\u003csub\\u003erange\\u003c/sub\\u003e, but four individuals had w\\u0026thinsp;=\\u0026thinsp;0.82\\u0026ndash;0.92 while one individual had w\\u0026thinsp;=\\u0026thinsp;0.24. We did not observe a relationship between w and standard ellipse area or convex hull area.\\u003c/p\\u003e\"},{\"header\":\"Discussion\",\"content\":\"\\u003cp\\u003eEcological theory suggests generalists with large ecological niches are more likely to persist through stochastic processes. However, there is growing evidence that many generalist populations are comprised individual specialists (Bolnick et al., \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2002\\u003c/span\\u003e). The stable isotope analysis of dental collagen from shark teeth provides multiple measurements per individual and can elucidate the extent of individual and population-level variation (Zeichner et al. \\u003cspan citationid=\\\"CR63\\\" class=\\\"CitationRef\\\"\\u003e2017\\u003c/span\\u003e; Matich et al. \\u003cspan citationid=\\\"CR30\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e; Shipley et al. \\u003cspan citationid=\\\"CR46\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e). This study of the Suruga Bay shark community reveals a large variation in isotopic niche width. Generally, δ\\u003csup\\u003e15\\u003c/sup\\u003eN values increase with total length, suggesting correspondence of trophic level and size, but there is substantial variation within individuals (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e). Our results demonstrate that individuals within a species have different isotopic niche widths (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig4\\\" class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003e), which does not necessarily correspond with the species-level niche width or overlap between individuals within a species (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e). The variation within individuals and among species indicates a continuum of generalists and specialists with a complex and diverse food web.\\u003c/p\\u003e \\u003cdiv id=\\\"Sec9\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eEcological Niche Width with Standard Ellipse Area (SEA\\u003csub\\u003ec\\u003c/sub\\u003e)\\u003c/h2\\u003e \\u003cp\\u003eWe estimated species-level isotopic niche using standard ellipse area (SEA\\u003csub\\u003ec\\u003c/sub\\u003e) to reduce errors associated with sample size. While this metric accounts for sample size bias, we found that species with a greater total length diversity among individuals also had the largest standard ellipse area. This pattern reinforces that many sharks are gape-limited predators and undergo ontogenetic dietary shifts (Heupel et al., \\u003cspan citationid=\\\"CR18\\\" class=\\\"CitationRef\\\"\\u003e2014\\u003c/span\\u003e), which is supported in this study by the significant relationship between total length and δ\\u003csup\\u003e15\\u003c/sup\\u003eN values (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e). The largest sharks in this study are the Needle Dogfish, which were near maximum adult size, but did not have the largest total niche width based on standard ellipse area (SEA\\u003csub\\u003ec\\u003c/sub\\u003e=1.96). A telemetric study of Needle Dogfish in Suruga Bay found bimodal depth preference (i.e., 300\\u0026ndash;400 and 580-620m) but little horizontal movement (Yano \\u0026amp; Tanaka, 1986); the limited range of habitat is reflected in its relatively low SEA\\u003csub\\u003ec\\u003c/sub\\u003e. In contrast, the Sharpnose Sevengill shark had the largest length range (78.3\\u0026ndash;117.5 cm), which spans the size at maturity (95\\u0026ndash;105 cm for females and 70\\u0026ndash;85 cm in males) (Tanaka \\u0026amp; Mizue, \\u003cspan citationid=\\\"CR50\\\" class=\\\"CitationRef\\\"\\u003e1977\\u003c/span\\u003e), and largest standard ellipse area (SEA\\u003csub\\u003ec\\u003c/sub\\u003e=3.26). Previous studies found evidence of an ontogenetic shift in Sharpnose Sevengill diet (Barnett et al., \\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e; Braccini, \\u003cspan citationid=\\\"CR7\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e), which likely accounts for the large isotopic niche exhibited in this study. The largest size distribution in this study was among Smooth hammerhead (58.4\\u0026ndash;106.1 cm) but the estimated isotopic niche width (SEA\\u003csub\\u003ec\\u003c/sub\\u003e=1.46) only reflects juveniles since the individuals sampled were substantially smaller than total length at maturity (250\\u0026ndash;260 cm; Miller, \\u003cspan citationid=\\\"CR31\\\" class=\\\"CitationRef\\\"\\u003e2016\\u003c/span\\u003e). These comparisons of standard ellipse area among species imply the importance of size and ontogeny on the overall niche width sharks. We expect the actual isotopic niche to be larger for the species that we had limited representation, such as Spinner Shark, Rough Dogfish, and Japanese Velvet Dogfish. An assessment of population-level isotopic niche width is necessary to compare within vs. between individual variation, which is the greatest asset of using shark teeth as a substrate for stable isotope analysis.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec10\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eIndividual Variability with Convex Hull Area (CHA)\\u003c/h2\\u003e \\u003cp\\u003eWe used convex hull area to investigate how individuals parse the species-level isotopic niches. Using convex hull area as a metric for determining niche width is often criticized for biased niche geometry due to outlying data points and inconsistent sample sizes (Shipley and Matich \\u003cspan citationid=\\\"CR45\\\" class=\\\"CitationRef\\\"\\u003e2020\\u003c/span\\u003e). However, convex hull areas are well suited to shark teeth because the same number of possible data points is controlled by the number of teeth available, and within a shark species the number of series is relatively constant (i.e., 3\\u0026ndash;5), so sample size bias is of less concern. Through teeth, we can compare convex hull areas of individuals within a species. Individuals that behave as generalists will have larger convex hull areas, whereas individual specialists will have smaller convex hull area.\\u003c/p\\u003e \\u003cp\\u003eOur results indicate no relationship between individual- and species- level niche width as evidenced by convex hull area and standard ellipse areas, respectively, which suggests a continuum of ecological strategies spanning specialists to generalists in these adjacent shark communities within Suruga Bay. We chose to highlight the substantial individual-level variation within many species with convex hull area and compare to a species-level summary since this feature is uniquely captured in the stable isotope analysis of shark teeth. For example, individual Sharpnose Sevengill sharks have a convex hull area range of 0.2\\u0026ndash;5.65 (n\\u0026thinsp;=\\u0026thinsp;8) while Smooth Hammerhead have a convex hull area range of 0.02\\u0026ndash;1.10 (n\\u0026thinsp;=\\u0026thinsp;12). The differences in maximum convex hull area for these species indicate the extent of diet variation while the range demonstrates individual-level dietary differences. The range of convex hull area for each species loosely increases with number of individuals and given the wide range of individuals per species in this study, we are cautious to designate species as generalists or specialists with these estimates of convex hull area.\\u003c/p\\u003e \\u003cp\\u003e \\u003cb\\u003eOverlap among individuals within a species with Pianka\\u0026rsquo;s Measure (\\u003c/b\\u003ew\\u003cb\\u003e)\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003eA key feature of proposed quantitative comparisons of individual vs. population niche width is the extent of overlap (i.e., within vs. between individual component as outlined in Bolnick et al. \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2002\\u003c/span\\u003e). We use Pianka\\u0026rsquo;s measure to estimate this proportional overlap between individuals within a population while accounting for multivariate covariance (Pianka \\u003cspan citationid=\\\"CR36\\\" class=\\\"CitationRef\\\"\\u003e1974\\u003c/span\\u003e; Yeakel et al. \\u003cspan citationid=\\\"CR62\\\" class=\\\"CitationRef\\\"\\u003e2011\\u003c/span\\u003e). This metric complements convex hull area and standard ellipse area because it demonstrates the similarity among individuals within a population. In other words, Pianka\\u0026rsquo;s measure can help distinguish if a generalist population is composed of specialist individuals behaving differently or individuals are also generalists. The most notable result of Pianka\\u0026rsquo;s measure in this study is a broad range throughout both shark communities and within species that encompasses almost the entire possible range: 0.06\\u0026ndash;0.94 (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e). Some species featured in this study had small sample size (i.e., n \\u0026le; 3) and therefore their range of Pianka\\u0026rsquo;s measure was limited.\\u003c/p\\u003e \\u003cp\\u003eWhile the correspondence of increasing δ\\u003csup\\u003e15\\u003c/sup\\u003eN values with total length supports some influence of gape-limited predation among sharks in these ecosystems (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e), most prominent in our results is the variation among individuals. For example, Needle Dogfish have the largest total length, highest δ\\u003csup\\u003e15\\u003c/sup\\u003eN values, and Pianka\\u0026rsquo;s measure span 0.16\\u0026ndash;0.71, which suggests a range of foraging behaviors and/or preferences. We note the lack of correlation between Pianka\\u0026rsquo;s measure and convex hull area throughout our dataset, which suggests the extent of individual diet variation is not tightly coupled to niche breadth for an individual or population.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec11\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eComparing the ecology of sharks within Suruga Bay\\u0026rsquo;s habitats\\u003c/h2\\u003e \\u003cp\\u003eSuruga Bay is an ideal location to explore patterns in ecological organization among predators given the proximity of multiple marine habitats. The spatial heterogeneity of this region coupled with the diverse shark community results in resource partitioning as evidenced by differences in stable isotope composition of sharks in the four habitats (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e, Table\\u0026nbsp;\\u003cspan refid=\\\"Tab2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e). Further, the population vs. individual stable isotope variation for habitats within Suruga Bay resemble ecological models with patch formation and emergence of specialist competitors (Levin and Paine \\u003cspan citationid=\\\"CR28\\\" class=\\\"CitationRef\\\"\\u003e1974\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003e\\u003cem\\u003eEpipelagic -\\u003c/em\\u003e We sampled juvenile Spinner Shark, Smooth Hammerhead, and Dusky Shark in the epipelagic zone of Suruga Bay. Based on δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e15\\u003c/sup\\u003eN values, this habitat is well linked to the deep benthic habitat, but statistically different from the coastal and abyssal habitats. This dissociation between the epipelagic and coastal habitats is surprising since their proximity would suggest energy and resource exchange. However, the individuals featured in this study were all juveniles based on their total length (Compagno \\u003cspan citationid=\\\"CR12\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e). Further, it is likely that most individuals were young of the year given their total length compared to published the length at birth for each species (Joung et al., \\u003cspan citationid=\\\"CR22\\\" class=\\\"CitationRef\\\"\\u003e2005\\u003c/span\\u003e; Choi, \\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e; Rosa et al., \\u003cspan citationid=\\\"CR42\\\" class=\\\"CitationRef\\\"\\u003e2017\\u003c/span\\u003e; Joung et al., \\u003cspan citationid=\\\"CR23\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e). The δ\\u003csup\\u003e15\\u003c/sup\\u003eN values of these juvenile sharks likely reflect a maternal signal given their age (Olin et al. \\u003cspan citationid=\\\"CR35\\\" class=\\\"CitationRef\\\"\\u003e2011\\u003c/span\\u003e; Tamburin et al. \\u003cspan citationid=\\\"CR48\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e) and incorporation rate of dentin collagen (Zeichner et al. \\u003cspan citationid=\\\"CR63\\\" class=\\\"CitationRef\\\"\\u003e2017\\u003c/span\\u003e). There is previous evidence for long distance migration in Spinner Shark (Rigby et al., 2020), Smooth Hammerhead (Santos and Coelho \\u003cspan citationid=\\\"CR43\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e), and Dusky Shark (Rogers et al., \\u003cspan citationid=\\\"CR41\\\" class=\\\"CitationRef\\\"\\u003e2013\\u003c/span\\u003e). Further, studies from Korea and Taiwan on these species report the absence of the smallest size classes (Joung et al. \\u003cspan citationid=\\\"CR22\\\" class=\\\"CitationRef\\\"\\u003e2005\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR23\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e; Choi \\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e). It is possible that the stable isotope compositions in this study reflect adult diet in these other localities. The epipelagic habitat of Suruga Bay may serve as an important nursery for these species throughout the western North Pacific Ocean.\\u003c/p\\u003e \\u003cp\\u003e\\u003cem\\u003eCoastal -\\u003c/em\\u003e The two species from the coastal habitat, Japanese Topeshark and Starspotted Smooth-hound, are endemic to the western Pacific Basin and listed as endangered by the International Union for Conservation of Nature (Rigby et al., 2020; Walls et al., \\u003cspan citationid=\\\"CR56\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e). These two species exhibit a relatively narrow and overlapping range in δ\\u003csup\\u003e13\\u003c/sup\\u003eC values, which are distinct from all other habitats in Suruga Bay except the abyssal zone (Table\\u0026nbsp;\\u003cspan refid=\\\"Tab2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e). The Japanese Topeshark exhibits a smaller isotopic niche on the species and individual level based on standard ellipse and convex hull area (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e) but has higher δ\\u003csup\\u003e15\\u003c/sup\\u003eN values than the Starspotted Smooth-hound (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e). A previous study focused in the Seto Inland Sea, located southwest of Suruga Bay, found that Japanese Topeshark were only seasonally present and predominantly preyed on benthic cephalopod and fish whereas Starspotted Smooth-hound were present year around and fed on crustaceans and polycheates (Kamura and Hashimoto \\u003cspan citationid=\\\"CR24\\\" class=\\\"CitationRef\\\"\\u003e2004\\u003c/span\\u003e). Starspotted Smooth-hound are known to have variable diets; a comparison of stomach contents between five localities found differences in prey preference (i.e., mantis shrimp, crab, hermit crab, shrimps, crustacean fragments, and polychaetes) with less diversity in larger individuals (Yamaguchi and Taniuchi \\u003cspan citationid=\\\"CR57\\\" class=\\\"CitationRef\\\"\\u003e2000\\u003c/span\\u003e). In Suruga Bay, Starpotted Smooth-hound feed at a low trophic level (i.e., low δ\\u003csup\\u003e15\\u003c/sup\\u003eN values; Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e) and the variation within and among individuals suggest it is a true generalist with variable individual diet (i.e., larger convex hull area; Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig4\\\" class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003e) and extensive overlap within the population with Pianka\\u0026rsquo;s measure\\u0026thinsp;\\u0026gt;\\u0026thinsp;0.75 for four individuals (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003eC). The stable isotope composition of Japanese Topeshark in Suruga Bay reflects their diet of small fishes and cephalopods (Kamura and Hashimoto \\u003cspan citationid=\\\"CR24\\\" class=\\\"CitationRef\\\"\\u003e2004\\u003c/span\\u003e), which are higher trophic prey than consumed by Starspotted Smooth-hound. In addition, Japanese Topeshark are caught in deeper waters (Yano \\u0026amp; Kugai, \\u003cspan citationid=\\\"CR58\\\" class=\\\"CitationRef\\\"\\u003e1993\\u003c/span\\u003e), which often have food webs enriched in \\u003csup\\u003e13\\u003c/sup\\u003eC and \\u003csup\\u003e15\\u003c/sup\\u003eN compared to epipelagic waters (Davison et al., \\u003cspan citationid=\\\"CR13\\\" class=\\\"CitationRef\\\"\\u003e2013\\u003c/span\\u003e; Mintenbeck et al., \\u003cspan citationid=\\\"CR32\\\" class=\\\"CitationRef\\\"\\u003e2007\\u003c/span\\u003e). These data contribute to growing evidence of the importance of sharks and fish in transferring energy and nutrients to deeper marine habitats (Carlisle et al., \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e; Davison et al., \\u003cspan citationid=\\\"CR13\\\" class=\\\"CitationRef\\\"\\u003e2013\\u003c/span\\u003e; Trueman et al., 2014).\\u003c/p\\u003e \\u003cp\\u003e\\u003cem\\u003eDeep benthic -\\u003c/em\\u003e The deep benthic habitat of Suruga Bay is represented by the Shortspine Spurdog and Sharpnose Sevengill Shark. These two species differ in their distribution and stable isotope results provide new ecological insights. The Sharpnose Sevengill Shark is globally distributed in deep benthic habitat up to 1000m depth on the upper slope and has dietary data available from multiple regions (Barnett et al., \\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e; Finucci et al., 2020). Previous studies determined Sharpnose Sevengill Shark diet to specialize on fish, crustaceans, and cephalopods in the Mediterranean, central Eastern Atlantic, and southern Australia (Braccini \\u003cspan citationid=\\\"CR7\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; Barnett et al. \\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e). However, in the context of the Suruga Bay shark assemblage, Sharpnose Sevengill Sharks have the largest isotopic niche on both the population and individual-level based on standard ellipse area and convex hull area, respectively, with a high degree of overlap among individuals (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e, \\u003cspan refid=\\\"Fig4\\\" class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003e, \\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e). This high degree of individual variation is also supported by two specimens analyzed for compound specific isotope analysis of amino acids; the δ\\u003csup\\u003e15\\u003c/sup\\u003eN values for the baseline are similar, but trophic variation is high (Fujiwara et al. \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e). In contrast, the Shortspine Spurdog has a limited distribution in deep benthic habitats of the Northwestern Pacific Ocean (Finucci et al., 2020; Ziadi-K\\u0026uuml;nzli et al., \\u003cspan citationid=\\\"CR64\\\" class=\\\"CitationRef\\\"\\u003e2020\\u003c/span\\u003e). The three specimens of Shortspine Spurdog in this study are immature females based on total length (Taniuchi and Tachikawa \\u003cspan citationid=\\\"CR51\\\" class=\\\"CitationRef\\\"\\u003e1997\\u003c/span\\u003e) and their δ\\u003csup\\u003e15\\u003c/sup\\u003eN values suggests a lower trophic level diet than the Sharpnose Sevengill but similar to the Japanese Topeshark in the coastal habitat (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e). Further, the Shortspine Spurdog has a constrained isotopic niche based on dentin δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e15\\u003c/sup\\u003eN values; this species has a smaller standard ellipse area and convex hull area than the Sharpnose Sevengill but also has high overlap with Pianka\\u0026rsquo;s measure\\u0026thinsp;\\u0026gt;\\u0026thinsp;0.50 (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e). The species within the deep benthic habitat have different population- and individual-level isotopic niches, but individuals within each species have a similar feeding ecology and exhibit a high degree of overlap in their isotopic composition.\\u003c/p\\u003e \\u003cp\\u003e\\u003cem\\u003eAbyssal -\\u003c/em\\u003e The deepest habitat of Suruga Bay is its central trough where the Japanese Velvet Dogfish, Roughskin Dogfish, Rough Longnose Dogfish, and Needle dogfish inhabit (Yano \\u0026amp; Tanaka, \\u003cspan citationid=\\\"CR59\\\" class=\\\"CitationRef\\\"\\u003e1983\\u003c/span\\u003e). The specimens for each species represent a relatively narrow range of total length and are fully mature adults so there is minimal ontogenetic insight from their stable isotope composition. Generally, the diet of Squaliformes is known to be fish and squid, but more specific diet data is sparse given that many stomachs are emptied as specimens are brought to the surface (Yano \\u0026amp; Tanaka, \\u003cspan citationid=\\\"CR59\\\" class=\\\"CitationRef\\\"\\u003e1983\\u003c/span\\u003e). The δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e15\\u003c/sup\\u003eN values from dentin collagen suggest there are differences in ecological niche among species as well as extensive individual-level variation within species. Our results indicate Needle Dogfish to occupy the largest isotopic niche as a species in the abyssal habitat with a standard ellipse area\\u0026thinsp;=\\u0026thinsp;2.0, but this may also be a function of the relatively high sample size (N\\u0026thinsp;=\\u0026thinsp;8; Table\\u0026nbsp;\\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e). The convex hull areas for individual Needle Dogfish spanned the largest range within this habitat and the extent of overlap among individuals varied widely (Table\\u0026nbsp;\\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e, Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e). Our study only included two specimens of Japanese Velvet Dogfish, but its diet is completely undescribed to date (Rigby et al. \\u003cspan citationid=\\\"CR40\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e). The Japanese Velvet Dogfish had elevated δ\\u003csup\\u003e15\\u003c/sup\\u003eN values, which is likely a result of feeding in the abyssal food web (Mintenbeck et al. 2015; Trueman et al., 2014) rather than high trophic level given that the specimens caught were \\u0026lt;\\u0026thinsp;100cm (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e). This species had the smallest isotopic niche and complete overlap in isotopic composition among individuals (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e). While these traits could be due to low sample size of Japanese Velvet Dogfish, we also only sampled two individual Roughskin Dogfish. These Roughskin Dogfish specimens produced similar results for species- and individual-level isotopic niche with their standard ellipse area and convex hull area, respectively (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e), but each specimen had different δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e15\\u003c/sup\\u003eN distributions from dentin collagen and therefore diverged in their overlap. This variation among individuals aligns with a previous result from compound specific isotope analysis of amino acids that indicated similar baselines but different trophic level from two other specimens caught in Suruga Bay (Fujiwara et al. \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e). The final species caught in the abyssal habitat is the Rough Longnose Dogfish, which has reported distribution data but no published record of diet (Compagno \\u003cspan citationid=\\\"CR12\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e; Carpenter and Garilao \\u003cspan citationid=\\\"CR10\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e). The isotopic niche for Rough Longnose Dogfish are similar to the Roughskin Dogfish on the species- and individual-level as well as extent of overlap among individuals (Table\\u0026nbsp;\\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e; Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e). However, the Rough Longnose Dogfish has the lowest mean δ\\u003csup\\u003e15\\u003c/sup\\u003eN values from dentin collagen of all species within the abyssal habitat, which could indicate foraging on prey from a shallower depth. Previous studies featuring deep water consumers and stable isotope analysis demonstrate the importance of diel-vertical migration, which transfers nutrients and links epipelagic, deep benthic, and abyssal marine habitats (Carlisle et al., \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e; Trueman et al., 2014). Although this study presents stable isotope compositions of consumers without prey data, the assessments individual vs. population variation provides an ecological context to evaluate resource use, ecological niche, and food web structure, which are substantial contributions for these species that are largely classified as \\u0026ldquo;data deficient\\u0026rdquo; and/or \\u0026ldquo;vulnerable\\u0026rdquo; (Froese and Pauly \\u003cspan citationid=\\\"CR16\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e).\\u003c/p\\u003e \\u003c/div\\u003e\"},{\"header\":\"Conclusions\",\"content\":\"\\u003cp\\u003eEssentially all sharks are carnivorous and occupy upper trophic levels within marine ecosystems, but the more subtle ecological differences between species as well as within and among individuals remains elusive. Here, we examine ecological niche using stable isotope analysis from dentin collagen, which provides a more nuanced perspective of diet and habitat with multiple measurements of carbon and nitrogen isotope composition per individual. We compare within vs. between individual variation using a suite of computational metrics without assumptions related to tissue specific discrimination factors or incorporation rates. Our stable isotope results indicate substantial variation in δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e15\\u003c/sup\\u003eN values for the shark community in adjacent habitats of Suruga Bay, Japan. A general trend in increasing δ\\u003csup\\u003e15\\u003c/sup\\u003eN values with total length (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e) suggest gape limited predation. In addition, we found a range of isotopic niche widths among species (e.g., standard ellipse area) and individuals (e.g., convex hull area), but no correlation between these ecological levels of organization. For example, Smooth Hammerhead and Needle Dogfish are generalist species with largest standard ellipse area, but individual convex hull areas vary in their size and distribution (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig4\\\" class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003e), which indicates some niche partitioning. However, it is important to note the differences among individuals as evidenced by the distribution of Pianka\\u0026rsquo;s measure (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e). Acknowledging this individual variation has ecological, evolutionary, and conservation implications to consider in future studies.\\u003c/p\\u003e\"},{\"header\":\"Declarations\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eAcknowledgements\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eWe thank A. Cruz Diaz and L. Jimenez who were instrumental in collecting stable isotope data; C. Cochran, M. Morris, and P. Valencia Landa for their assistance weighing samples; and L. Meyer for their ideas and feedback. We would also like to thank the Undergraduate Research Opportunities Center at UC Merced for supporting the students involved with this research during the Summer Undergraduate Research Institute and Fellowship.\\u003c/p\\u003e\\n\\u003cp\\u003eFunding: This research was funded in part by a National Science Foundation\\u0026rsquo;s East Asia and Pacific Summer Institutes (NSF 0513060) and start-up funds from the University of California, Merced to SLK.\\u003c/p\\u003e\\n\\u003cp\\u003eConflicts of interest/Competing: The authors have no conflicts of interest.\\u003c/p\\u003e\\n\\u003cp\\u003eEthics approval: All applicable institutional and/or national guidelines for the care and use of animals were followed; in Japan, sampling from fishery discard does not require scientific collection permits or ethical approval in Japan.\\u003c/p\\u003e\\n\\u003cp\\u003eConsent to participate: NA\\u003c/p\\u003e\\n\\u003cp\\u003eAvailability of data and material: Data available from the Dryad Digital Repository\\u0026nbsp;https://doi.org/\\u0026nbsp;10.6071/M34370 (Kim, Valdez, Trayler, \\u0026amp; Tanaka, in review).\\u003c/p\\u003e\\n\\u003cp\\u003eCode availability: NA\\u003c/p\\u003e\\n\\u003cp\\u003eAuthors\\u0026apos; contributions: SLK and ST conceived the ideas and designed methodology; ST collected samples; ADV collected the data; ADV, RBT, and SLK analyzed the data; ADV, RBT and, SLK wrote the manuscript. All authors contributed critically to the drafts and gave final approval for publication. All authors also state they have no conflict of interest.\\u0026nbsp;\\u003c/p\\u003e\"},{\"header\":\"References\",\"content\":\"\\u003col\\u003e\\u003cli\\u003e\\u003cspan\\u003eBarnett A, Braccini JM, Awruch CA, Ebert DA (2012) An overview on the role of Hexanchiformes in marine ecosystems: Biology, ecology and conservation status of a primitive order of modern sharks. J Fish Biol 80:966\\u0026ndash;990. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1111/j.1095-8649.2012.03242.x\\u003c/span\\u003e\\u003cspan address=\\\"10.1111/j.1095-8649.2012.03242.x\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eBaum JK, Worm B (2009) Cascading top-down effects of changing oceanic predator abundances. J Anim Ecol 78:699\\u0026ndash;714. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1111/j.1365-2656.2009.01531.x\\u003c/span\\u003e\\u003cspan address=\\\"10.1111/j.1365-2656.2009.01531.x\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eBolnick DI, Yang LHY, Fordyce JA, Davis JM, Svanb\\u0026auml;ck R (2002) MEASURING INDIVIDUAL-LEVEL RESOURCE SPECIALIZATION. 83:2936\\u0026ndash;2941\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eBolnick DI, Svanb\\u0026auml;ck R, Fordyce JA, Yang LH, Davis JM, Hulsey CD, Forister ML (2003) The ecology of individuals: Incidence and implications of individual specialization. Am Nat 161:1\\u0026ndash;28. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1086/343878\\u003c/span\\u003e\\u003cspan address=\\\"10.1086/343878\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eBolnick DI, Svanb\\u0026auml;ck R, Ara\\u0026uacute;jo MS, Persson L (2007a) Comparative support for the niche variation hypothesis that more generalized populations also are more heterogeneous. Proc Natl Acad Sci U S A 104:10075\\u0026ndash;10079. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1073/pnas.0703743104\\u003c/span\\u003e\\u003cspan address=\\\"10.1073/pnas.0703743104\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eBolnick DI, Svanb\\u0026auml;ck R, Ara\\u0026uacute;jo MS, Persson L (2007b) Comparative support for the niche variation hypothesis that more generalized populations also are more heterogeneous. Proc Natl Acad Sci U S A 104:10075\\u0026ndash;10079. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1073/PNAS.0703743104\\u003c/span\\u003e\\u003cspan address=\\\"10.1073/PNAS.0703743104\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eBraccini JM (2008) Feeding ecology of two high-order predators from south-eastern Australia: The coastal broadnose and the deepwater sharpnose sevengill sharks. Mar Ecol Prog Ser 371:273\\u0026ndash;284. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.3354/meps07684\\u003c/span\\u003e\\u003cspan address=\\\"10.3354/meps07684\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eBump JK, Fox-Dobbs K, Bada JL, Koch PL, Peterson RO, Vucetich JA (2007) Stable isotopes, ecological integration and environmental change: Wolves record atmospheric carbon isotope trend better than tree rings. Proc R Soc B Biol Sci 274:2471\\u0026ndash;2480. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1098/rspb.2007.0700\\u003c/span\\u003e\\u003cspan address=\\\"10.1098/rspb.2007.0700\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eCarlisle AB, Allan EA, Kim SL, Meyer L, Port J, Scherrer S, O\\u0026rsquo;Sullivan J (2021) Integrating multiple chemical tracers to elucidate the diet and habitat of Cookiecutter Sharks. Sci Rep 11:11809. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1038/s41598-021-89903-z\\u003c/span\\u003e\\u003cspan address=\\\"10.1038/s41598-021-89903-z\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eCarpenter KE, Garilao CV (2021) Deania hystricosa (Garman, 1906) Rough longnose dogfish. In: FishBase\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eChoi Y (2018) A Pregnant Smooth Hammerhead Sphyrna zygaena, Collected in the Western Coastal Water, Korea. Korean J Ichthyol 30:167\\u0026ndash;169. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.35399/isk.30.3.6\\u003c/span\\u003e\\u003cspan address=\\\"10.35399/isk.30.3.6\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eCompagno LJV (2001) Sharks of the world: an annotated and illustrated catalogue of shark species known to date. Food \\\\\\u0026amp; Agriculture Org\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eDavison PC, Checkley DM, Koslow JA, Barlow J (2013) Carbon export mediated by mesopelagic fishes in the northeast Pacific Ocean. Prog Oceanogr 116:14\\u0026ndash;30. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1016/J.POCEAN.2013.05.013\\u003c/span\\u003e\\u003cspan address=\\\"10.1016/J.POCEAN.2013.05.013\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eFinucci B, Barnett A, Bineesh KK, Cheok J, Cotton CF, Kulka DW, Neat FC, Rigby CL, Tanaka S, Walker TI (2020a) Heptranchias perlo, Sharpnose Sevengill Shark. In: The IUCN Red List of Threatened Species\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eFinucci B, Cheok J, Cotton CF, Kulka DW, Neat FC, Pacoureau N, Rigby CL, Tanaka S, Walker TI (2020b) Squalus mitsukurii, Shortspine Spurdog Assessment. In: The IUCN Red List of Threatened Species\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eFroese R, Pauly D (2021) Fishbase\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eFujiwara Y, Kawato M, Poulsen JY, Ida H, Chikaraishi Y, Ohkouchi N, Oguri K, Gotoh S, Ozawa G, Tanaka S, Miya M, Sado T, Kimoto K, Toyofuku T, Tsuchida S (2021) Discovery of a colossal slickhead (Alepocephaliformes: Alepocephalidae): an active-swimming top predator in the deep waters of Suruga Bay, Japan. Sci Rep 11:1\\u0026ndash;16. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1038/s41598-020-80203-6\\u003c/span\\u003e\\u003cspan address=\\\"10.1038/s41598-020-80203-6\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eHeupel MR, Knip DM, Simpfendorfer CA, Dulvy NK (2014) Sizing up the ecological role of sharks as predators. Mar Ecol Prog Ser 495:291\\u0026ndash;298. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.3354/meps10597\\u003c/span\\u003e\\u003cspan address=\\\"10.3354/meps10597\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eIwata T, Shinomura Y, Natori Y, Igarashi Y, Sohrin R, Suzuki Y (2005) Relationship between salinity and nutrients in the subsurface layer in the Suruga Bay. J Oceanogr 61:721\\u0026ndash;732. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1007/s10872-005-0079-2\\u003c/span\\u003e\\u003cspan address=\\\"10.1007/s10872-005-0079-2\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eJackson AL, Inger R, Parnell AC, Bearhop S (2011) Comparing isotopic niche widths among and within communities: SIBER - Stable Isotope Bayesian Ellipses in R. J Anim Ecol 80:595\\u0026ndash;602. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1111/j.1365-2656.2011.01806.x\\u003c/span\\u003e\\u003cspan address=\\\"10.1111/j.1365-2656.2011.01806.x\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eJapan Meteorological Agency (2020) Climate Change Monitoring Report\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eJoung SJ, Liao YY, Liu KM, Chen CT, Leu LC (2005) Age, growth, and reproduction of the spinner shark, Carcharhinus brevipinna, in the northeastern waters of Taiwan. Zool Stud 44:102\\u0026ndash;110\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eJoung SJ, Chen JH, Chin CP, Liu KM (2015) Age and growth of the dusky shark, Carcharhinus obscurus, in the Western North Pacific Ocean. Terr Atmos Ocean Sci 26:153\\u0026ndash;160. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.3319/TAO.2014.10.15.01(Oc)\\u003c/span\\u003e\\u003cspan address=\\\"10.3319/TAO.2014.10.15.01(Oc)\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eKamura S, Hashimoto H (2004) The food habits of four species of triakid sharks, Triakis scyllium, Hemitriakis japanica, Mustelus griseus and Mustelus manazo, in the central Seto Inland Sea, Japan. Fish Sci 70:1019\\u0026ndash;1035. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1111/j.1444-2906.2004.00902.x\\u003c/span\\u003e\\u003cspan address=\\\"10.1111/j.1444-2906.2004.00902.x\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eKim SLSL, Del Rio CMCM, Casper D, Koch PLPL (2012) Isotopic incorporation rates for shark tissues from a long-Term captive feeding study. J Exp Biol 215:2495\\u0026ndash;2500. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1242/jeb.070656\\u003c/span\\u003e\\u003cspan address=\\\"10.1242/jeb.070656\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eLayman CA, Albrey Arrington D, Monta\\u0026ntilde;a CG, Monta\\u0026ntilde;a M, Post DM (2007a)CAN STABLE ISOTOPE RATIOS PROVIDE FOR COMMUNITY-WIDE MEASURES OF TROPHIC STRUCTURE?\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eLayman CA, Quattrochi JP, Peyer CM, Allgeier JE (2007b) Niche width collapse in a resilient top predator following ecosystem fragmentation. Ecol Lett 10:937\\u0026ndash;944. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1111/j.1461-0248.2007.01087.x\\u003c/span\\u003e\\u003cspan address=\\\"10.1111/j.1461-0248.2007.01087.x\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eLevin SA, Paine RT (1974) Disturbance, patch formation, and community structure. Proc Natl Acad Sci U S A 71:2744\\u0026ndash;2747. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1073/pnas.71.7.2744\\u003c/span\\u003e\\u003cspan address=\\\"10.1073/pnas.71.7.2744\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eMartinez del Rio C, Dugelby B, Foreman D, Miller B, Noss R, Phillips M (2001) The importance of large carnivores to healthy ecosystems. Endanger Species Updat 18:202\\u0026ndash;210\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eMatich P, Bizzarro JJ, Shipley ON (2021) Are stable isotope ratios suitable for describing niche partitioning and individual specialization? Ecol Appl 31:1\\u0026ndash;8. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1002/eap.2392\\u003c/span\\u003e\\u003cspan address=\\\"10.1002/eap.2392\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eMiller MH (2016) Endangered Species Act status review report: smooth hammerhead shark. Sphyrna zygaena)\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eMintenbeck K, Jacob U, Knust R, Arntz WE, Brey T (2007) Depth-dependence in stable isotope ratio δ15N of benthic POM consumers: The role of particle dynamics and organism trophic guild. Deep Sea Res Part I Oceanogr Res Pap 54:1015\\u0026ndash;1023. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1016/J.DSR.2007.03.005\\u003c/span\\u003e\\u003cspan address=\\\"10.1016/J.DSR.2007.03.005\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eMunroe SEM, Simpfendorfer CA, Heupel MR (2014) Defining shark ecological specialisation: Concepts, context, and examples. Rev Fish Biol Fish 24:317\\u0026ndash;331\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eMyers RA, Baum JK, Shepherd TD, Powers SP, Peterson CH (2007) Cascading effects of the loss of apex predatory sharks from a coastal ocean. Sci (80-) 315:1846\\u0026ndash;1850. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1126/science.1138657\\u003c/span\\u003e\\u003cspan address=\\\"10.1126/science.1138657\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eOlin JA, Hussey NE, Fritts M, Heupel MR, Simpfendorfer CA, Poulakis GR, Fisk AT (2011) Maternal meddling in neonatal sharks: Implications for interpreting stable isotopes in young animals. Rapid Commun Mass Spectrom 25:1008\\u0026ndash;1016. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1002/rcm.4946\\u003c/span\\u003e\\u003cspan address=\\\"10.1002/rcm.4946\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003ePianka ER (1974) Niche overlap and diffuse competition. Proc Natl Acad Sci U S A 71:2141\\u0026ndash;2145. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1073/pnas.71.5.2141\\u003c/span\\u003e\\u003cspan address=\\\"10.1073/pnas.71.5.2141\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eQuevedo M, Svanb\\u0026auml;ck R, Ekl\\u0026ouml;av P (2009) Intrapopulation niche partitioning in a generalist predator limits food web connectivity. Ecology 90:2263\\u0026ndash;2274. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1890/07-1580.1\\u003c/span\\u003e\\u003cspan address=\\\"10.1890/07-1580.1\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eRigby CL, Bin Ali A, Bineesh KK, Chen X, Derrick D, Dharmadi, Ebert DA, Fahmi, Fernando D, Gautama DA, Haque AB, Ho H, Hsu H, Krajangdara T, Maung A, Vo VQ, Sianipar A, Tanay D, Utzurrum JAT, Yuneni RR, Zhang J (2020a) Mustelus manazo, Starspotted Smooth-hound. In: The IUCN Red List of Threatened Species\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eRigby CL, Carlson J, Smart JJ, Pacoureau N, Herman K, Derrick D, Brown E (2020b) Spinner Shark Carcharhinus brevipinna. The IUCN Red List of Threatened Species\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eRigby CL, Walls RHL, Derrick D, Dyldin YV, Herman K, Ishihara H, Jeong C-H, Semba Y, Tanaka S, Volvenko IV, Yamaguchi A (2021) Scymnodon ichiharai Japanese Velvet Dogfish. 8235\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eRogers PJ, Huveneers C, Goldsworthy SD, Mitchell JG, Seuront L (2013) Broad-scale movements and pelagic habitat of the dusky shark Carcharhinus obscurus off Southern Australia determined using pop-up satellite archival tags. Fish Oceanogr 22:102\\u0026ndash;112. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1111/fog.12009\\u003c/span\\u003e\\u003cspan address=\\\"10.1111/fog.12009\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eRosa D, Coelho R, Fernandez-Carvalho J, Santos MN (2017) Age and growth of the smooth hammerhead, Sphyrna zygaena, in the Atlantic Ocean: comparison with other hammerhead species. Mar Biol Res 13:300\\u0026ndash;313. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1080/17451000.2016.1267366\\u003c/span\\u003e\\u003cspan address=\\\"10.1080/17451000.2016.1267366\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eSantos CC, Coelho R (2018) Migrations and habitat use of the smooth hammerhead shark (sphyrna zygaena) in the atlantic ocean. PLoS ONE 13:1\\u0026ndash;17. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1371/journal.pone.0198664\\u003c/span\\u003e\\u003cspan address=\\\"10.1371/journal.pone.0198664\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eShinohara G, Shirai SM, Nazarkin MV, Yabe M (2011) Preliminary List of the Deep-sea Fishes of the Sea of Japan. Bull Natl Museum Nat Sccience 37:35\\u0026ndash;62\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eShipley ON, Matich P (2020) Studying animal niches using bulk stable isotope ratios: an updated synthesis. Oecologia 193:27\\u0026ndash;51. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1007/s00442-020-04654-4\\u003c/span\\u003e\\u003cspan address=\\\"10.1007/s00442-020-04654-4\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eShipley ON, Henkes GA, Gelsleichter J, Morgan CR, Schneider EV, Talwar BS, Frisk MG (2021) Shark tooth collagen stable isotopes (δ15N and δ13C) as ecological proxies. J Anim Ecol 90:2188\\u0026ndash;2201. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1111/1365-2656.13518\\u003c/span\\u003e\\u003cspan address=\\\"10.1111/1365-2656.13518\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eSoule M, Stewart BR (2009) The American Society of Naturalists The \\\" Niche-Variation \\\" Hypothesis: A Test and Alternatives. 104:85\\u0026ndash;97\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eTamburin E, Kim SL, Elorriaga-Verplancken FR, Madigan DJ, Hoyos-Padilla M, S\\u0026aacute;nchez-Gonz\\u0026aacute;lez A, Hern\\u0026aacute;ndez-Herrera A, Castillo-Geniz JL, Godinez-Padilla CJ, Galv\\u0026aacute;n-Maga\\u0026ntilde;a F (2019) Isotopic niche and resource sharing among young sharks (carcharodon carcharias and isurus oxyrinchus) in baja California, Mexico. Mar Ecol Prog Ser 613:107\\u0026ndash;124. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.3354/meps12884\\u003c/span\\u003e\\u003cspan address=\\\"10.3354/meps12884\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eTanaka K, Michida Y, Komatsu T, Ishigami K (2009) Spreading of river water in Suruga Bay. J Oceanogr 65:165\\u0026ndash;177. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1007/s10872-009-0016-x\\u003c/span\\u003e\\u003cspan address=\\\"10.1007/s10872-009-0016-x\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eTanaka S, Mizue K (1977) Studies on Sharks-XI: Reproduction in Female Heptranchias perlo. Bull Fac Fish Nagasaki Univ 42:1\\u0026ndash;9\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eTaniuchi T, Tachikawa H (1997) Geographical variation in age and growth of Squalus mitsukurii (Elasmobranchii: Squalidae) in north Pacific. In: Proceedings of 5th Indo-Pacific Fish Conference, Noum\\u0026eacute;a. pp\\u0026nbsp;321\\u0026ndash;328\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eToyoda T, Sakamoto K, Usui N, Hirose N, Tanaka K, Katsumata T, Takahashi D, Niki M, Kutsuwada K, Miyama T, Nakano H, Urakawa LS, Komatsu KK, Kawakami Y, Yamanaka G (2021) Surface-Layer Circulations in Suruga Bay Induced by Intrusions of Kuroshio Branch Water. Front Mar Sci 8:1243. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.3389/FMARS.2021.721500/BIBTEX\\u003c/span\\u003e\\u003cspan address=\\\"10.3389/FMARS.2021.721500/BIBTEX\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eTrueman CN, Johnston G, O\\u0026rsquo;Hea B, MacKenzie KM (2014a) Trophic interactions of fish communities at midwater depths enhance long-term carbon storage and benthic production on continental slopes. Proc R Soc B Biol Sci 281:1\\u0026ndash;10. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1098/rspb.2014.0669\\u003c/span\\u003e\\u003cspan address=\\\"10.1098/rspb.2014.0669\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eTrueman CN, Johnston G, O\\u0026rsquo;hea B, Mackenzie KM (2014b) Trophic interactions of fish communities at midwater depths enhance long-term carbon storage and benthic production on continental slopes. Proc R Soc B Biol Sci 281:1\\u0026ndash;10. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1098/rspb.2014.0669\\u003c/span\\u003e\\u003cspan address=\\\"10.1098/rspb.2014.0669\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eUrakawa H, Yoshida T, Nishimura M, Ohwada K (2001) Characterization of microbial communities in marine surface sediments by terminal-restriction fragment length polymorphism (T-RFLP) analysis and quinone profiling. Mar Ecol Prog Ser. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.3354/meps220047\\u003c/span\\u003e\\u003cspan address=\\\"10.3354/meps220047\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eWalls RHL, Rigby CL, Derrick D, Dyldin YV, Herman K, Ishihara H, Jeong C-H, Semba Y, Tanaka S, Volvenko IV, Yamaguchi A (2021) Hemitriakis japanica, Japanese Topeshark. In: The IUCN Red List of Threatened Species\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eYamaguchi A, Taniuchi T (2000) Food variations and ontogenetic dietary shift of the starspotted-dogfish Mustelus manazo at five locations in Japan and Taiwan. Fish Sci 66:1039\\u0026ndash;1048. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1046/j.1444-2906.2000.00166.x\\u003c/span\\u003e\\u003cspan address=\\\"10.1046/j.1444-2906.2000.00166.x\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eYano K, Kugai K (1993) Deep-sea chondrichthyans collected from the waters around the Okinawa Islands:. results of catch analysis of bottom longlines\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eYano K, Tanaka S (1983) Biological Studies on Squaloid Sharks from Suruga Bay, Japan. In: Proceedings 2nd North Pacific Aquaculture Symposium. Tokyo and Shimizu, Japan, pp\\u0026nbsp;407\\u0026ndash;414\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eYano K, Tanaka S (1984) Some Biological Aspects of the Deep Sea Squaloid Shark Centroscymnus from Suruga Bay, Japan. Nippon SUISAN GAKKAISHI. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.2331/suisan.50.249\\u003c/span\\u003e\\u003cspan address=\\\"10.2331/suisan.50.249\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eYano K and ST (1986) A telemetric study on the movements of the deep sea squaloid shark, Centrophorus acus. Indo-Pacific Fish Biology: Proceed. Sec. Inter. Conf. on Indo-Pacific Fishes. Ichthyological Society of Japan, Tokyo, pp 372\\u0026ndash;380\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eYeakel JD, Novak M, Guimar\\u0026atilde;es PR, Dominy NJ, Koch PL, Ward EJ, Moore JW, Semmens BX (2011) Merging resource availability with isotope mixing models: The role of neutral interaction assumptions. PLoS ONE 6:1\\u0026ndash;8. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1371/journal.pone.0022015\\u003c/span\\u003e\\u003cspan address=\\\"10.1371/journal.pone.0022015\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eZeichner SS, Colman AS, Koch PL, Polo-Silva C, Galv\\u0026aacute;n-Maga\\u0026ntilde;a F, Kim SL (2017) Discrimination factors and incorporation rates for organic matrix in shark teeth based on a captive feeding study. Physiol Biochem Zool 90:257\\u0026ndash;272. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1086/689192\\u003c/span\\u003e\\u003cspan address=\\\"10.1086/689192\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eZiadi-K\\u0026uuml;nzli F, Soliman T, Imai H, Sakurai M, Maeda K, Tachihara K (2020) Re-evaluation of deep-sea dogfishes (genus Squalus) in Japan using phylogenetic inference. Deep Res Part I Oceanogr Res Pap 160:103261. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1016/j.dsr.2020.103261\\u003c/span\\u003e\\u003cspan address=\\\"10.1016/j.dsr.2020.103261\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e\\u003c/ol\\u003e\"}],\"fulltextSource\":\"\",\"fullText\":\"\",\"funders\":[],\"hasAdminPriorityOnWorkflow\":false,\"hasManuscriptDocX\":true,\"hasOptedInToPreprint\":true,\"hasPassedJournalQc\":\"\",\"hasAnyPriority\":false,\"hideJournal\":false,\"highlight\":\"\",\"institution\":\"\",\"isAcceptedByJournal\":false,\"isAuthorSuppliedPdf\":false,\"isDeskRejected\":\"\",\"isHiddenFromSearch\":false,\"isInQc\":false,\"isInWorkflow\":false,\"isPdf\":false,\"isPdfUpToDate\":true,\"isWithdrawnOrRetracted\":false,\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"marine-biology\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":false,\"externalIdentity\":\"mabi\",\"sideBox\":\"Learn more about [Marine Biology](https://www.springer.com/journal/227)\",\"snPcode\":\"227\",\"submissionUrl\":\"https://submission.nature.com/new-submission/227/3\",\"title\":\"Marine Biology\",\"twitterHandle\":\"\",\"acdcEnabled\":true,\"dfaEnabled\":true,\"editorialSystem\":\"em\",\"reportingPortfolio\":\"Springer Hybrid\",\"inReviewEnabled\":true,\"inReviewRevisionsEnabled\":false},\"keywords\":\"Isotopic Niche, Mesopredator, Time Series, Teeth, Japan\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-1631337/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-1631337/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"\\u003cp\\u003eDietary variability impacts food web dynamics and resource partitioning among individuals and species in a community. However, it is difficult to characterize the ecological niche of sharks, a mobile and long-lived predator. Stable isotope analysis allows the quantification of niche width since it incorporates both environmental and biological variation. Carbon isotope composition varies between marine productivity regimes while nitrogen isotope composition indicates trophic position, but baseline can vary with seasonal or regional shifts. We sampled dental collagen for stable isotope analysis. The conveyor-like growth of shark teeth provides a time series allowing for multiple measurements per individuals.\\u003c/p\\u003e \\u003cp\\u003eWe sampled 59 individuals from 11 species captured in 2005 at Suruga Bay, Japan (34\\u0026deg;50'59.99\\\" N 138\\u0026deg;32'59.99\\\" E). We estimated three ecological metrics based on stable isotope composition\\u0026mdash;standard ellipse area, convex hull area, and Pianka\\u0026rsquo;s measure\\u0026mdash;which elucidated the extent of ecological variation and allowed comparisons among individuals and species. Our results show a significant positive correlation between dental collagen δ\\u003csup\\u003e15\\u003c/sup\\u003eN values and total length (r\\u003csup\\u003e2\\u003c/sup\\u003e\\u0026thinsp;=\\u0026thinsp;0.23; \\u003cem\\u003ep\\u003c/em\\u003e\\u0026thinsp;=\\u0026thinsp;2⨉10\\u003csup\\u003e\\u0026minus;\\u0026thinsp;16\\u003c/sup\\u003e), but individual variability had a low coefficient of determination. The variation in isotopic niche within and among individuals as well between species across all habitat types suggest that many species spanned the generalist \\u0026ndash; specialist continuum. Our findings indicate there are subtle ecological differences between species and among individuals; multiple measurements of carbon and nitrogen composition from multiple teeth series indicate variable ecological niches. Comparing patterns across habitats suggests sharks have complex food web dynamics with extensive individual- and species-level variation.\\u003c/p\\u003e\",\"manuscriptTitle\":\"The generalist – specialist continuum for sharks based on stable isotope analysis of dental collagen\",\"msid\":\"\",\"msnumber\":\"\",\"nonDraftVersions\":[{\"code\":1,\"date\":\"2022-05-12 16:08:01\",\"doi\":\"10.21203/rs.3.rs-1631337/v1\",\"editorialEvents\":[{\"type\":\"communityComments\",\"content\":0},{\"type\":\"editorInvitedReview\",\"content\":\"\",\"date\":\"2022-05-10T12:12:12+00:00\",\"index\":0,\"fulltext\":\"\"},{\"type\":\"reviewersInvited\",\"content\":\"\",\"date\":\"2022-05-09T14:49:45+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorAssigned\",\"content\":\"\",\"date\":\"2022-05-07T07:40:03+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"submitted\",\"content\":\"Marine Biology\",\"date\":\"2022-05-06T19:16:28+00:00\",\"index\":\"\",\"fulltext\":\"\"}],\"status\":\"published\",\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"marine-biology\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":false,\"externalIdentity\":\"mabi\",\"sideBox\":\"Learn more about [Marine Biology](https://www.springer.com/journal/227)\",\"snPcode\":\"227\",\"submissionUrl\":\"https://submission.nature.com/new-submission/227/3\",\"title\":\"Marine Biology\",\"twitterHandle\":\"\",\"acdcEnabled\":true,\"dfaEnabled\":true,\"editorialSystem\":\"em\",\"reportingPortfolio\":\"Springer Hybrid\",\"inReviewEnabled\":true,\"inReviewRevisionsEnabled\":false}}],\"origin\":\"\",\"ownerIdentity\":\"f02769c2-c036-4662-bdd8-5718e7ab3970\",\"owner\":[],\"postedDate\":\"May 12th, 2022\",\"published\":true,\"recentEditorialEvents\":[],\"rejectedJournal\":[],\"revision\":\"\",\"amendment\":\"\",\"status\":\"under-review\",\"subjectAreas\":[],\"tags\":[],\"updatedAt\":\"2024-09-09T04:20:35+00:00\",\"versionOfRecord\":[],\"versionCreatedAt\":\"2022-05-12 16:08:01\",\"video\":\"\",\"vorDoi\":\"\",\"vorDoiUrl\":\"\",\"workflowStages\":[]},\"version\":\"v1\",\"identity\":\"rs-1631337\",\"journalConfig\":\"researchsquare\"},\"__N_SSP\":true},\"page\":\"/article/[identity]/[[...version]]\",\"query\":{\"redirect\":\"/article/rs-1631337\",\"identity\":\"rs-1631337\",\"version\":[\"v1\"]},\"buildId\":\"WrCJVZZCHTDjtuVLN7oU0\",\"isFallback\":false,\"isExperimentalCompile\":false,\"dynamicIds\":[84888],\"gssp\":true,\"scriptLoader\":[]}","source_license":"CC-BY-4.0","license_restricted":false}