{"paper_id":"09d55261-e44d-419c-a821-6e2cadbe467d","body_text":"Diet and Feeding Strategy of Northern Pike, Esox lucius L., 1758 Inhabiting A Deep Dam Lake from Located Central Anatolia, TÜRKİYE | 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 Article Diet and Feeding Strategy of Northern Pike, Esox lucius L., 1758 Inhabiting A Deep Dam Lake from Located Central Anatolia, TÜRKİYE Okan YAZICIOĞLU, Ramazan YAZICI, Abdülkadir YAĞCI, Mahmut YILMAZ This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4656714/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Fish samples were collected monthly from Dam Lake from September 2015 to August 2016 and a total of 133 northern pike, Esox lucius individuals were examined for this study. The feeding intensity showed the highest value during summer (FI = 1.59) while the lowest value was during winter (FI = 0.51). Temperature was identified as the most critical environmental variable influencing feeding intensity. The high similarity in the diet of northern pike was observed between seasons. Stomach content analysis indicated that this species consumed only prey fishes. The most eaten of prey fishes were the Tinca tinca contributing 44.83% by number and 56.16% by frequency of occurrence. There was little variation in feeding features between seasons. The northern pike more specialized on T.tinca and Atherina. boyeri . According to the findings of the study, Esox lucius was a primary predator and showed a specialist feeding behavior, feeding only on fish (mainly T. tinca and A. boyeri ). Environmental prey abundance did not affect the prey selection of this fish species in Sıddıklı Dam Lake. Diet feeding strategy feeding habits food items predator fish Esox lucius Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Piscivorous fishes are typically considered the most influential top predator or keystone within aquatic ecosystems. These fishes directly and indirectly influence species occupying lower trophic levels and create top-down trophic cascades impacting the entire food-web. Also, aquatic keystone predators that the top level of the food web (piscivorous fish) may have strong effects on the structure, function, and biodiversity of aquatic habitats such as freshwater and coastal ecosystems (Nilsson et al. 2023 ). Northern pike ( Esox lucius ) is a widely distributed freshwater fish in the northern hemisphere (Craig 2008 ), and it has commercial value in Türkiye (Yazicioglu et al. 2018 ), also to be used for recreational fisheries in different areas of world (Didenko and Gurbyk 2016 ; Trella and Woƚos 2021 ). The northern pike is an important keystone piscivore in many aquatic ecosystems (Kekäläinen et al. 2008 ) and a top-level predator in aquatic food chains in the northern hemisphere (Winfield et al. 2012 ). It has a significant influence on the species composition, density, distribution, and structure of the fish populations inhabiting different aquatic habitats (Craig 2008 ). Pike is a predator that attacks from ambush and spends less energy for catching, handling, and swallowing of the prey (Nilsson and Brönmark 1999 ). Pike prefer shallow vegetated and low-flow habitats. Because northern pike needs these habitats where can hide and ambush its prey (Casselman and Lewis 1996 ). Scientific knowledge on food and feeding habits of fish is both an important condition for increasing fish production (Malik et al. 2019 ) and important for evaluating the ecological role and position of the species in the food web of ecosystems (Saikia 2015 ). Besides, Knowledge of the food habits and diets of a fish species is important to understanding many aspects of fish biology, physiology, and behavior. Food and feeding habits of the fishes be affected throughout the day, season, body size, habitat, environmental condition, and food sources available (Malik et al. 2019 ). Therefore, evaluating nutritional studies according to these basic factors is very important in terms of fish biology and fisheries management. Information on the feeding features of top predator or piscivorous species, such as diet composition, feeding habits, and feeding strategy, is useful to assess the role of freshwater fishes in the ecosystem. Information obtained from feeding studies can be used for sustainable fisheries management and protection of aquatic ecosystems. The main objective of this study was to comparatively describe the seasonal variations in diet composition, and feeding features such as feeding habits and strategy, and food preferences of top predator northern pike. Material and Method Study Area and Sampling Sıddıklı Küçükboğaz Dam Lake (formerly called Karababa Dam) is a zonal dam on Körpeli Boğaz Creek at the border of the Province of Kırşehir located from Central Anatolian region of Türkiye. This dam lake is composed of clay and rock, with a central core. Dam construction began in 1991 and was finished in 2002. The lake dam is made of clay and filled with rock. It has a 1.62 km 2 surface area with an active water level of 25.3 hm 3 (Akkan et al. 2018 ). Pike gill nets were simultaneously used to collect fish samples monthly from September 2015 to August 2016 at Sıddıklı Küçükboğaz Dam Lake. The nets were set at dusk, left in the water for 12-hour min, and hauled at 08:00–09:00 h. The nets were composed of pelagic gill nets with bar mesh sizes (knot to knot) of 20, 25, 30, 35, 40, 45, 55, 65, and 80 mm. All operations on fish capture and dead fish studied in the laboratory were carried out in accordance with animal health and welfare ethical rules. This study was approved by the animal experiments local ethics committee (document no: 68429034/05). Additionally, our study complies with ARRIVE 2.0 guidelines. Some physical and chemical parameters of the lake water, such as dissolved oxygen (DO), temperature, salinity, pH, conductivity, total dissolved solid (TDS) were measured monthly from September 2015 to August 2016 (Yazıcı 2018 ) and environmental variables were given Table 1 . Table 1 Monthly changes in some physicochemical parameters of surface water in Sıddıklı Dam Lake from September 2015 to August 2016 Months Water Parameters Temperature pH DO Salinity TDS Conductivity September 2015 22.91 8.22 9.38 0.48 6.63 940.00 October 15.77 7.51 14.90 0.52 6.73 850.00 November 10.40 8.41 7.16 0.78 9.95 1100.00 December 3.68 8.41 11.03 0.63 8.29 750.00 January 2016 3.10 8.21 11.79 0.40 5.35 820.00 February 7.40 8.15 11.76 0.44 5.77 890.00 March 8.78 8.25 9.24 0.35 4.55 700.00 April 14.93 8.16 8.79 0.34 4.48 690.00 May 18.10 8.31 7.18 0.34 4.52 700.00 June 20.85 8.40 6.86 0.32 4.28 650.00 July 24.48 8.31 6.02 0.33 4.42 680.00 August 23.05 8.37 5.97 0.33 4.72 700.00 Laboratory Methods and Stomach Content Analysis A total of one hundred thirty-three (133) samples were examined for stomach analysis. In the laboratory, all fish samples were measured in cm (total length) and weighed in grams. The stomachs were removed by dissection from each specimen and preserved in a 4% formaldehyde solution for afterward analysis. The stomachs were opened during the examination, and the prey was identified, weighed in grams, sorted, and classified to the lowest taxonomic level before being preserved in 70% ethanol. Also, full and empty stomach weights were measured with a precision of 0.01 g. When a prey item was mostly digested, identification of prey fishes was based on scales, pharyngeal bones (cyprinids), opercular bones, vertebrae, and the location of the mouth and eyes (Pavlović et al. 2015 ). To compare the change of feeding intensity between seasons the fullness index (FI = weight of stomach content/ weight of fish *100) and the vacuity index (VI%= the number of empty stomachs/total number of the examined stomachs* 100) were calculated (De Santis and Volta 2021 ). Low feeding activity is considered when high vacuity index is observed (Martinho et al., 2012 ). Kruskal-Wallis test (K-W test) was used to analyze whether seasons affected the fullness index (FI) in northern pike. Spearman’s rank correlation was used to determine the relationship between fullness index (FI) and physicochemical parameters of surface water. Also, A chi-square test (χ2) was applied to determine the vacuity index (%VI) changes between the seasons. Traditional methods such as percentage frequency of occurrence (FO%= number of stomachs containing prey i/number of stomachs with any food item* 100), numerical percentage (N%= number of prey i/total number of all prey items* 100), and percentage by weight (W%= weight of prey i/total weight of all prey items* 100) of dietary analysis were used to determine feeding features (Hyslop 1980 ). The main food items were identified using index of relative importance (IRI) of Pinkas et al. ( 1971 ), as modified by Hacunda ( 1981 ). $$\\:IRI=\\left(\\%N+\\%W\\right)\\times\\:\\%FO$$ This index has been expressed as the percentage of each prey item; $$\\:\\%IRI=\\left(IRI/\\sum\\:IRI\\right)x\\:100$$ For computation of the relative amounts of intraspecific competition between seasons, simplified Morisita-Horn index (C h ) based on %N data was used (Horn 1966 ): $$\\:{C}_{h}=\\frac{2\\:\\left(\\sum\\:{p}_{ij}{p}_{ik}\\right)}{\\sum\\:{p}_{ij}^{2}+\\sum\\:{p}_{ik}^{2}}$$ where C h is the Morisita-Horn index of diet overlap between different seasons p ij is the proportion of food type “i” f the total food quantity by seasons “j,” p ik is the proportion of food type “i” of the total food used by seasons “k” and, n is the total number of food types. The degree of overlap was classified as low (0.0–0.29), moderate (0.30–0.59), and high (0.60–1.00) (Langton 1982 ). The selectivity of prey categories in the diet was statistically tested with x 2 -test, utilizing Pearre's C index of prey selection. The index value ( Va ) varies from − 1 (prey avoidance) to + 1 (prey selection), with 0 indicating random prey selection (Pearre 1982 ). $$\\:Va=\\frac{({a}_{d}\\times\\:{b}_{e})-({a}_{e}\\times\\:{b}_{d})}{\\sqrt{a\\times\\:b\\times\\:d\\times\\:e}}$$ where Va is Pearre’s index for pike selection of prey a, ad is the abundance of prey a in the diet, be is the abundance of all other prey in the environment, bd is the abundance of all other prey in the diet, and ae is the abundance of prey a in the environment. Values without subscripts are expressed as follows: $$\\:a={a}_{d}+{a}_{e}$$ $$\\:b={b}_{d}+{b}_{e}$$ $$\\:d={a}_{d}+{b}_{d}$$ $$\\:e={a}_{e}+{b}_{e}$$ The statistical significance of the selection index value ( Va ) was tested using the chi-squared test. $$\\:{x}^{2}=n\\times\\:{C}^{2}$$ The value of relative abundance (ae) used in the prey selection index for each fish species inhabiting Sıddıklı Dam Lake was obtained from Yazıcı ( 2018 ). Feeding strategy was determined from the plot of percentages of prey-specific abundance (Pi%) against frequency of occurrence (FO). Prey specific abundance, the percent numerical abundance of a prey item averaged over the stomach samples in which it occurs, was calculated using the methodology in Amundsen et al. ( 1996 ). $$\\:Pi=\\left(\\frac{\\sum\\:Si}{\\sum\\:Sti}\\right)*100$$ where Pi = Prey specific abundance of prey i; Si = Abundance of prey in stomachs and Sti = Total abundance of prey in predators that contain prey i. For specialist feeding, prey items appear in the upper part of the plot, while generalists have all prey points in the lower part. Results During this study, 133 specimens of Esox lucuis were collected. Of these, 73 specimen (54.9%) had food item, while 60 (45.1%) had empty stomachs. The feeding intensity of E. lucius according to season was shown in Fig. 1 . The vacuity index (VI%) was highest during winter (49.2%) and lowest during summer (28.6%) (Fig. 1 ). VI% values did not reveal significant differences between seasons (x 2 = 2.832, p > 0.05). The fullness index which is a real indicator for feeding intensity exhibited the highest values during Summer (FI = 1.59) and Autumn (FI = 1.13), while the lowest values were during winter (FI = 0.51) and Spring (FI = 1.07) (Fig. 1 ). The change between seasons in the vacuity index was not found to be statistically significant. (K-W test, p > 0.05). Spearman rank correlation analysis indicated that there was a positive correlation between fullness index (FI) and temperature (rs = 0.117), pH (rs = 0.05), total dissolved solid (TDS) (rs = 0.061), and conductivity (rs = 0.064), but not statistically significant (p > 0.05). The negative correlation between fullness index (FI) and dissolved oxygen (rs = -0.058) and salinity (rs = -0.173) was detected. The differences were statistically significant in the salinity parameter (p < 0.05), while differences were not statistically significant in the dissolved oxygen parameter (p > 0.05). General diet composition The diet of pike comprised six (6) food items, containing only prey fish species. The diet of 73 pike samples included 116 prey items, comprising Tinca tinca (52), Atherina boyeri (40), Cyprinus carpio (8), Squalius seyhanensis (8), Alburnus orontis (5) and, unidentified fish (3). (Table 1 ). T. tinca was the dominant prey in number with 44.83%, followed by A. boyeri (N = 34.48%). The frequency of occurrence of T. tinca was the highest (56.16%), followed by A. boyeri (27.4%). The total wet weight of 116 prey items was 675.88 g. T. tinca was the most frequently consumed prey item with 66.68% by weight, followed by S. seyhanensis with 15.7%. According to the relative importance index (IRI), the most important food items was T. tinca (79.51%), followed by A. boyeri (14.8%) (Table 2 ). Table 2 General diet composition of pike ( Esox lucius ) in Sıddıklı Küçükboğaz Dam Lake. n, prey number; N%, numerical percentage; W, prey weight; W%, percentage by weight; O, frequency of occurrence; FO%, percentage frequency of occurrence; IRI, index of relative importance. Food items n N% W W% O FO% IRI IRI% T.tinca 52 44.83 450.66 66.68 41 56.16 6262.402 79.51 A. boyeri 40 34.48 54.41 8.05 20 27.4 1165.322 14.80 C. carpio 8 6.9 36.2 5.35 8 10.96 134.26 1.70 S. seyhanensis 8 6.9 106.08 15.7 8 10.96 247.696 3.14 A. orontis 5 4.3 13.38 1.98 5 6.85 43.018 0.55 Unidentified fish 3 2.59 6.12 0.91 3 4.11 14.385 0.18 Fish remains - - 9.03 1.33 5 6.85 9.1105 0.12 Toplam 116 100 675.88 100 7876.193 100 There was a little seasonal variation in food habits of Esox lucius in studied area (Fig. 2 ). T.tinca were the dominant prey group during all seasons, particularly from spring (IRI %= 79.71) to summer (IRI% = 80.28). A. boyeri and S. seyhanensis were also present in the diet throughout the year, with a peak value recorded in winter (IRI %= 27.38) and spring (IRI%= 9.39) respectively. C. carpio were present in contents during all seasons except autumn, while A. orontis were only found in autumn. These prey items were observed smaller quantities in diet. Morisita-Horn index showed a high degree of dietary overlap between seasons, ranging from 0.7754 to 0.9675 (Table 3 ). These overlap values indicated that fishes fed on similar food items when living in this habitat throughout the year. It was show that the least of diet similarity (0.7754) was in autumn-winter. In contrast, the food of northern pike showed an extreme high dietary overlap (0.9675%) in spring-summer. Table 3 Results of Morisita-Horn indices for the diets overlap between seasons in northern pike. C h Spring Summer Autumn Winter Spring - Summer 0.9675* - Autumn 0.8820* 0.8705* - Winter 0.8840* 0.9657* 0.7754* - * Statistically significant The dietary pattern of Esox lucius is graphically showed in Fig. 3 where the prey-specific abundance (Pi) is plotted against the frequency of occurrence (FO%). The feeding strategy of the northern pike showed variety for prey items. The diet of northern pike was mostly based on rare species that were eaten occasionally and in relatively small amounts, such as Cyprinus carpio , Squalius seyhanensis , Alburnus orontis and unidentified fish, except for Tinca tinca and Atherina boyeri , which tended to be dominant prey. The population of the northern pike can be considered as a generalist predator with a relatively broad niche width, hovewer population consists of some specialized individuals that feed widely on T. tinca (i.e., prey with a high prey-specific abundance and more than 50% frequency of occurrence) and A. boyeri (i.e., prey with a high prey-specific abundance and less than 40% frequency of occurrence). T. tinca and A. boyeri were located in the upper middle part of the diagram, and this situation demonstrated the importance of these prey items in the diet of northern pike, as well as a trend toward population specialization regarding this prey. These specialized fish shift the feeding strategy of northern pike towards a higher between-phenotype contribution to the utilization of the resource gradient or niche width (Fig. 3 ). In other words, for a generalist predator like E. lucius , the sharing of food resources is ensured by certain individuals who specialize in consuming limited but plentiful prey. According to the prey selection index (C), there was positive selection for Tinca tinca (C = 0.5233) and Alburnus orontis (C = 0.1114), negative selection for Cyprinus c arpio (C= -0.1193) and Squalius seyhanensis (C= -0.02523), and close to neutral selection for Atherina boyeri (C = 0.009478) by pike individuals. Estimated prey selection indices of the prey fish were statistically insignificant (P > 0.05), except T.tinca (Fig. 4 ). Discussion This study provided information on the food items and feeding habits of Esox lucius , a predatory fish species caught from Sıddıklı Dam Lake in Türkiye Inland Water. During the study, 73 (64.9%) specimens had food items in their stomach while 60 (45.1%) individuals possessed empty. It was found that the empty stomach rate (VI%) of pike varied between 10.24% and 77% in studies conducted in different habitats (Soupir et al., 2000 ; Yılmaz and Polat 2005 ; Alp et al. 2008 ; Yılmaz et al. 2010; Yazicioglu et al. 2018 ). Chapman et al. ( 1989 ) reported that the proportion of empty stomachs in northern pike is positively related to the frequency of occurrence of prey fish in stomach. Arrington et al. ( 2002 ) stated that the presence of a high percentage of empty stomach is a common situation in piscivorous fish. Similarly, the value of VI expressed as the percentage of empty stomachs was high in study area and it was generally consistent with the results of previous studies (Kangur andKangur 1998 ; Didenko and Gurbyk 2016 ). Most empty stomachs are probably related to nets stay time of fish and the digestive process after the fish are caught. The high rate of empty stomachs may also be due to the sampling method (gill nets) that causes predator fish to vomit their stomach contents (Didenko and Gurbyk 2016 ). Our findings showed that the values of the fullness index (FI) follow an inverse trend to vacuity index values (VI%). This finding is consistent with results for previous studies in different species or habitats (Giarrizzo and Saint-Paul 2008 ; Yazicioglu et al. 2018 ). The vacuity index (VI) is an inverse indication of feeding intensity which vary according to variations in the spawning time (Yazıcıoğlu et al. 2016 ), seasonal changes in water temperature (Okgerman et al. 2013 ) and food item (Yazicioglu et al. 2018 ). Seasonal variations in feeding intensity show an increase in the fullness index during summer while, this index be detected a decrease in the winter in this study. Similarly, Bregazzi and Kenndy (1980) determined that feeding increased in summer and autumn, with less intensive feeding during the spawning season and in winter. Alp et al. ( 2008 ) reported that the percentage of empty stomachs of this species in Çivril Lake was highest in winter and that it fed more intensively during the spring and summer seasons. Reason of lower feeding intensity in winter is most likely due to lower water temperatures which slow down metabolism. Similar to the results of our study, the main environmental factor affecting feeding intensity of fishes is water temperature (Okgerman et al. 2013 ; Yazicioglu et al. 2022). Northern pike consumed a narrow range of prey items in this study and their diet consisted of only prey fishes. The northern pike exhibited piscivorous feeding features in this area, and the present results are similar to the finding of Liao et al. ( 2002 ) in Spirit Lake (Iowa, USA), Yilmaz et al. ( 2010 ) in Lake Uluabat (Bursa, Türkiye), Yılmaz and Enver (2014) in Sıdıklı Dam Lake (Kırşehir, Türkiye), and Pavlović et al ( 2015 ) in Šumarice Reservoir (Serbia). It is thought that the consumption of only fish species in the study is due to the size distribution of the studied samples and the larger body size of food fish compared to benthic invertebrates. Additionally, feeding exclusively on fish may be due to the small surface area of the aquatic habitat studied and the high fish density. However, previous studies reported that this species displayed a highly diversified diet and consumed a broad range of prey items from invertebrate to vertebrate (Soupir et al. 2000 ; Alp et al. 2008 ; Yazicioglu et al. 2018 ; Cathcart et al. 2019 ). In this study, a total of five different food fish were detected in the stomach of the pike and the most important prey fishes were T. tinca and A. boyeri , respectively. Mêrő ( 2015 ) reported that a total of 51 prey-fish species were observed in the stomachs of pike in different studies. The differences of prey fishes in diet composition are mainly due to availability of prey items in different habitats. Cannibalism detected generally in northern pike populations (Alp et al. 2008 ; Cathcart et al. 2019 ), however intraspecific predation (cannibalism) did not occur in the northern pike population in this study. Other researchers also not observed cannibalism among northern pike in different freshwater ecosystems (Yilmaz et al. 2010 ; Pavlović et al. 2015 ; Jacobson et al. 2019 ). The reason for the absence of cannibalism is due to the abundance of prey fishes in the lake and the low density of predator species. Furthermore, Craig ( 1996 ) found that the occurrence of cannibalism varied according on the availability of prey fish and pike density. The feeding habits of pike and their predation on fish showed little change depending on the seasons. The most consumed food in all seasons was T. tinca , followed by A. boyeri and S. seyhanensis , respectively. Many studies have stated that there are seasonal changes in the diet of pike (Liao et al. 2002 ; Alp et al. 2008 ). The seasonal variations in diet can be associated to the density, abundance, and availability of prey items. The results of this study showed that some of the analyzed specimens specialized on certain types of prey fish, whereas the entire sample seems to have a generalized feeding strategy. This feeding strategy can be deduced from the fact that a few prey items have a high prey-specific abundance (%Pi) and a low frequency of occurrence. The generalist feeding strategy of the northern pike is likely associated with the fact that the pike is an opportunistic feeder (Sandlund et al. 2016 ) and can shift prey consumed depending on prey availability (including behavior) and abundance (Craig 2008 ). The northern pike some individuals tended to exhibit a specialist feeding strategy towards T. tinca and A. boyeri in all seasons, while other prey fishes had low prey-specific abundance and were generally rare prey for pike with generalist feeding strategies. Pike exhibited a similar feeding strategy in The Natural Park of the Ruidera Lakes. This species showed a specialized feeding strategy towards crayfish, but a generalized strategy towards other food items (Elvira et al. 1996 ). Cathcart et al. ( 2019 ) indicated that feeding strategies of northern pike inhabiting 31 different waterbodies in Alaska differed among size classes, and generally feeding strategy showed specialization toward vertebrate prey, generalization toward macroinvertebrate prey, except dragonflies. Yazicioglu et al ( 2018 ) reported that changes in feeding features of northern pike living in Ladik Lake depending on size groups (generalist feeding features in small individuals and specialists in large samples). In present study, Tinca tinca (C = 0.5233) and Alburnus orontis (C = 0.1114) were the most preferred prey fish. Cyprinus carpio (C= -0.1193) and Squalius seyhanensis were negatively selected by pike. A. boyeri , the most abundant species in the lake, is close to neutral selection by pike. Environmental prey abundance was not to shape the prey selection of this fish species in Sıddıklı Dam Lake. Similar results regarding prey preference of northern pike were also reported in Çivril lake (Alp et al. 2008 ). Alp et al. ( 2008 ) reported that Chondrostoma meandrense, Gobio gobio and Tinca tinca were the most preferred food species in Çivril (Denizli) Lake, and Hemigrammocapoeta kemali and Aphanius anatolicus were not preferred. The littoral zone of lakes and dam lakes is important for fish species, especially herbivorous and omnivorous species due to protection from predatory fish, breeding, and nesting or shelter. For marine and freshwater ecosystems, aquatic vegetation that supports a varied and abundant fish population is an important biogenic habitat (Akın and Turgut 2003 ). Since northern pike are ambush predators that need aquatic vegetation to hide from their prey items, their density is highest in the littoral zone of shallow lotic and lentic ecosystems (Haught and Von Hippel 2011 ). Thus, they can exhibit predation on Tinca tinca and Alburnus orontis that are abundant littoral zone where aquatic plants occur. The fact that carp is not preferred by pike may be due to the high body height of C. carpio . Factors such as the soft rays (Eklöv and Hamrin 1989 ; Tyus and Beard 1990 ) and body height (Alp et al. 2008 ) of the prey fishes play a role in the pike's preference for its prey. Size, shape, and swimming speed of prey, as well as the quantity and quality of prey available and the level of predator satiation and competition a can play a role in the prey's selective by predator. Mouth form and size of predator can be effective in choosing the type and size of food (Juanes et al. 2002 ). Magnhagen and Heibo ( 2001 ) determined that gape size of the predator and the body depth of the prey are the main factors deciding whether a northern pike can ingest a potential prey fish. Pavlović et al. ( 2015 ) reported that northern pike can shift prey preference due to changes in the abundance and vulnerability of prey items in aquatic environments. Aquatic vegetation provides a significant biogenic habitat for marine and freshwater ecosystems (Akın and Turgut 2003 ) and reduces the foraging success of predatory fish by obstructing the vision and attack movements of predators. Therefore, the capture time increase (Gotceitas 1990 ). Similarly, it is thought that the negative selection of S. seyhanensis and the natural selection of A. boyeri may be due to the abundance of aquatic vegetation in the coastal area of the lake. Conclusion, this study presented the food items, feeding intensity and feeding habits of northern pike during various seasons and feeding strategy in Sıddıklı Dam Lake, Türkiye. Furthermore, it also revealed the relationships between environmental parameters and feeding intensity. Esox lucius showed variations in feeding intensity at seasonal. It was observed that environmental food abundance had no effect on the prey preference of this fish species in the research area. It is thought that the morphological structure of prey fish mostly affects food preference. The present findings on the feeding feature of Esox lucius could contribute to the existing knowledge on sustainable management of this potentially prey fishes with economic and ecological value. Declarations Acknowledgments We would like to thank local fisherman Ali Aydemir for helping us catch fish. Funding This work was financially supported by Kırşehir Ahi Evran University, project no. PYO.MYO.4001.15.001. Data availability The datasets are available upon request from the corresponding author. Ethical approval Fish catching and laboratory procedures for this study were approved by the animal experiments local ethics committee (document no: 68429034/05). Consent of publication Not applicable. Competing interests The authors declare that no conflicting interests exist References Akın Ş. Turgut E (2003) A review paper on the effects of aquatic vegetation on predator-prey interactions. Journal of Agricultural Faculty of Gaziosmanpaşa University 20(2): 49-53. Akkan T, Yazicioglu O, Yazici R, Yilmaz M (2018) Assessment of irrigation water quality of Turkey using multivariate statistical techniques and water quality index: Sıddıklı Dam Lake. Desalination and Water Treatment. https://dx.doi.org/10.5004/dwt.2018.22302 Alp A, Yeğen V, Yağcı-Apaydın M, Uysal R, Biçen E, Yağcı A (2008). Diet Composition and Prey Selection of Pike, Esox lucius, in Çivril Lake, Turkey. 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Eklöv P, Hamrin SF (1989) Predatory Efficiency and Prey Selection: Interactions Between Pike Esox lucius , Perch Perca fluviatilis and Rudd Scardinius erythrophthalmus . Oikos. http://dx.doi.org/10.2307/3565330 Elvira B, Nicola GG, Almodovar A (1996) Pike and Red Swamp Crayfish: A New Case on Predator-Prey Relationship Between Aliens in Central Spain. Journal of Fish Biology. http://dx.doi.org/10.1111/j.1095-8649.1996.tb01438.x Giarrizzo T, Saint-Paul U (2008) Ontogenetic and seasonal shifts in the diet of the pemecou sea catfish Sciades herzbergii (Siluriformes: Ariidae), from a macrotidal mangrove creek in the Curuçá estuary, Northern Brazil. Revista de Biología Tropical 56(2): 861-873. Gotceitas V (1990) Variation in plant stem density and its effects on foraging success of juvenile bluegill sunfish. Environ Biol Fish 27(1): 63-70. Hacunda JS (1981) Trophic Relationships Among Demersal Fishes in A Coastal Area of the Gulf of Marine. Fishery Bulletin 79(4): 775-788. Haught S, Von Hippel FA (2011) Invasive pike establishment in Cook Inlet Basin lakes, Alaska: diet, native fish abundance and lake environment. Biological Invasions 13: 2103-2114. Horn HS (1966) Measurement of overlap in comparative ecological studies. The American Naturalist 100: 419-424 Hyslop EJ (1980) Stomach Contents Analysis-A Review of Methods and Their Application. Journal of Fish Biology. http://dx.doi.org/10.1111/j.1095-8649.1980.tb02775.x Jacobson P, Bergström U, Eklöf J (2019) Size-dependent diet composition and feeding of Eurasian perch ( Perca fluviatilis ) and northern pike ( Esox lucius ) in the Baltic Sea. Boreal Environment Research 24(1-6): 1. Juanes F, Buckel JA, Scharf FS (2002) Feeding ecology of piscivorous fishes. In: Hart PJB, Reynolds JD (eds) Handbook of fish biology and fisheries, Blackwell Publishing Company, Oxford, pp 267-279 Kangur A, Kangur P (1998) Diet Composition and Size-Related Changes in The Feeding of Pikeperch, Stizostedion lucioperca (Percidae) and Pike, Esox lucius (Esocidae) in The Lake Peipsi (Estonia). Italian Journal of Zoology. http://dx.doi.org/10.1080/11250009809386828 Kekäläinen J, Niva T, Huuskonen H (2008) Pike predation on hatchery-reared Atlantic salmon smolts in a northern Baltic River. Ecology of Freshwater Fish 17: 100-109. Langton RW (1982) Diet overlap between the Atlantic cod Gadus morhua , silver hake, Merluccius biliniaris and fifteen other northwest Atlantic fin fish. Fish Bull 80:745-759. Liao H, Pierce J, Larscheid G (2002) Diet Dynamics of The Adult Piscivorous Fish Community in Spirit Lake, Iowa, USA 1995-1997. Ecology of Freshwater Fish. http://dx.doi.org/10.1034/j.1600-0633.2002.00015.x Magnhagen C, Heibo E (2001) Gape Size Allometry in Pike Reflects Variation Between Lakes in Prey Availability and Relative Body Depth. Functional Ecology 15(6): 754-762. Malik DS, Sharma AK, Tyagi D (2019) Food and feeding habits of Tor tor (Hamilton, 1822) and Schizothorox richardsonii (Gray, 1832) inhibiting Bhagirathi River, Tehri Garhwal, India. International Journal of Science and Nature 10(2): 97-103 Martinho F, Sá C, Falcão J, Cabral HN, Pardal MÂ (2012) Comparative feeding ecology of two elasmobranch species, Squalus blainville and Scyliorhinus canicula , off the coast of Portugal. Fish. Bull 110:71-84. Mêrő TO (2015) The first recording of the threatened species, the European weather loach, Misgurnus fossilis (Berg, 1949), in the diet of the pike. Turkish Journal of Zoology 39(5): 967-970. Nilsson PA, Brönmark C (1999) Foraging among cannibals and kleptoparasites: effects of prey size on pike behavior. Behavioral Ecology 10(5): 557-566. Nilsson PA, Ranåker L, Hulthén K, Nilsson-Örtman V, Brönmark C, Brodersen J (2023) First-season growth and food of YOY pike ( Esox lucius ) are habitat specific within a lake. Fisheries Research. https://doi.org/10.1016/j.fishres.2022.106563 Okgerman HC, Yardimci CH, Dorak Z, Yilmaz N (2013) Feeding ecology of vimba ( Vimba vimba L., 1758) in terms of size groups and seasons in Lake Sapanca, northwestern Anatolia. Turkish Journal of Zoology 37(3): 288-297. Pavlović M, Simonović P, Stojković M, Simić V (2015) Analysis of diet of piscivorous fishes in Bovan, Gruža and Šumarice reservoir, Serbia. Iranian Journal of Fisheries Sciences 14(4): 908-923 Pearre SJR (1982) Estimating Prey Preference by Predators: Uses of Various Indices, and A Proposal of Another Based on x 2. Canadian Journal of Fisheries and Aquatic Sciences. http://dx.doi.org/10.1139/f82-122 Pinkas L, Oliphant MS, Iverson ILK (1971) Food Habits of Albacore, Bluefin Tuna, and Bonito in California Waters. Fish Bulletin 152: 1-105. Saikia SK (2015) Food and feeding of fishes. What do we need to know?. Transylvanian Review of Systematical and Ecological Research 17(1): 71-84. Sandlund OT, Museth J, Øistad S (2016) Migration, growth patterns, and diet of pike (Esox lucius) in a river reservoir and its inflowing river. Fisheries Research 173: 53-60. Soupir CA, Brown ML, Kallemeyn LW (2000) Trophic ecology of largemouth bass and northern pike in allopatric and sympatric assemblages in northern boreal lakes. Canadian Journal of Zoology 78(10): 1759-1766. Trella M, Woƚos A (2021) Size and selected characteristics of northern pike ( Esox lucius L.) commercial and angling catches in Polish inland waters over the long term. Fisheries Aquatic & Life 29: 108-123 Tyus HM, Beard JM (1990) Esox lucius (Esocidae) and Stizostedion vitreum (Percidae) in The Green River Basin, Colorado and Utah. Great Basin Naturalist 50(1): 33-39 Winfield IJ, Fletcher JM, Ben James J, (2012) Long‐term changes in the diet of pike ( Esox lucius ), the top aquatic predator in a changing Windermere. Freshwater Biology 57(2): 373-383. Yazıcı R (2018) Biological Properties of Wels Catfish ( Silurus glanis L., 1758) in Sıddıklı Küçükboğaz Dam. Dissertation, Kırşehir Ahi Evran University Yazici R, Yazicioğlu O, Yilmaz S, Polat N (2022) Food composition and feeding strategies of an invasive species, Carassius gibelio (Bloch, 1782) inhabiting a eutrophic lake in Middle Black Sea region. Indian Journal of Fisheries 69(2): 48-55. Yazıcıoğlu O, Yılmaz S, Yazıcı R, Erbaşaran M, Polat N (2016) Feeding ecology and prey selection of European perch, Perca fluviatilis inhabiting a eutrophic lake in northern Turkey. Journal of Freshwater Ecology 31(4): 641-651. Yazicioglu O, Polat N, Yilmaz S (2018) Feeding biology of pike, Esox lucius L., 1758 inhabiting Lake Ladik, Turkey. Turkish Journal of Fisheries and Aquatic Sciences 18(10): 1215-1226. Yilmaz M, Gaffaroglu M, Polat N, Emiroglu O, (2010) The Dietary Regime of The Pike ( Esox lucius L., 1758) in Lake Uluabat (Bursa, Turkey), Journal of Animal and Veterinary Advances 9 (3): 651-653. Yılmaz M, Polat N (2005) Digestive System Content of the Pike ( Esox lucius L., 1758) Living in Simenit Lake (Terme-Samsun). Fırat University Journal of Engineering Science 17(3): 589-598. Yılmaz M, Ünver E (2014) Feeding Dietary of Pike Esox lucius L.,1758 Inhabiting Sıdıklı Küçükboğaz Dam Lake. The Black Sea Journal of Sciences 4(10): 37-45 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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-4656714\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":true,\"archivedVersions\":[],\"articleType\":\"Article\",\"associatedPublications\":[],\"authors\":[{\"id\":333227372,\"identity\":\"00984db9-2830-447f-9951-7f2385474e32\",\"order_by\":0,\"name\":\"Okan YAZICIOĞLU\",\"email\":\"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA4ElEQVRIiWNgGAWjYDACHijNx8B8AEhJyBCvhY2BLQGkhQePWgwtPAbIfNyAn+fsMckfNTZ2bRI5n1/dqLHgYWA/fHQDPi2SvX1pEhLH0pLbJHK3WeccAzqMJy3tBj4tBud5zCQMGw4nswG1GOewAbVI8JgR1pII1pLzzDjnHzFazvaYSRxsOGwH1ML8OLeNCC2SPWeMLRuOpSWw8TwzY87tk+BhI+QXfp4cw5vAELPnZ09+/DnnW50cP/vhY3i1AAGLBJBIbABGDYgBjCDCgPkDkLCHMUbBKBgFo2AUYAAAL1FAUDampHkAAAAASUVORK5CYII=\",\"orcid\":\"\",\"institution\":\"Ahi Evran University\",\"correspondingAuthor\":true,\"prefix\":\"\",\"firstName\":\"Okan\",\"middleName\":\"\",\"lastName\":\"YAZICIOĞLU\",\"suffix\":\"\"},{\"id\":333227373,\"identity\":\"02855169-b764-40e5-b2fd-21866ef48796\",\"order_by\":1,\"name\":\"Ramazan YAZICI\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Ahi Evran University\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Ramazan\",\"middleName\":\"\",\"lastName\":\"YAZICI\",\"suffix\":\"\"},{\"id\":333227374,\"identity\":\"731bea06-86a5-4198-bda8-035269f9e777\",\"order_by\":2,\"name\":\"Abdülkadir YAĞCI\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Ministry of Agriculture and Forestry\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Abdülkadir\",\"middleName\":\"\",\"lastName\":\"YAĞCI\",\"suffix\":\"\"},{\"id\":333227375,\"identity\":\"11add4a4-816d-4331-bdbd-09cdbad11477\",\"order_by\":3,\"name\":\"Mahmut YILMAZ\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Ahi Evran University\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Mahmut\",\"middleName\":\"\",\"lastName\":\"YILMAZ\",\"suffix\":\"\"}],\"badges\":[],\"createdAt\":\"2024-06-28 20:53:27\",\"currentVersionCode\":1,\"declarations\":\"\",\"doi\":\"10.21203/rs.3.rs-4656714/v1\",\"doiUrl\":\"https://doi.org/10.21203/rs.3.rs-4656714/v1\",\"draftVersion\":[],\"editorialEvents\":[],\"editorialNote\":\"\",\"failedWorkflow\":false,\"files\":[{\"id\":62153486,\"identity\":\"97d3b18b-3ebb-481b-ad6a-1bc1b1dcf7bd\",\"added_by\":\"auto\",\"created_at\":\"2024-08-09 20:53:46\",\"extension\":\"png\",\"order_by\":1,\"title\":\"Figure 1\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":163429,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eThe mean fullness index (FI) and vacuity index (VI %) for seasons in northern pike inhabiting Sıddıklı Küçükboğaz Dam Lake.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Fig1.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4656714/v1/ef4170a38a3ce1372a8ed202.png\"},{\"id\":62153484,\"identity\":\"2b5532ab-9b55-4443-b709-dcb52453c401\",\"added_by\":\"auto\",\"created_at\":\"2024-08-09 20:53:46\",\"extension\":\"png\",\"order_by\":2,\"title\":\"Figure 2\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":203396,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eSeasonal diet composition of northern pike inhabiting Sıddıklı Dam Lake.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Fig2.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4656714/v1/de2204f11e76ca34de0bb86c.png\"},{\"id\":62153483,\"identity\":\"556f8496-4a42-44bf-9576-dd309d8f0838\",\"added_by\":\"auto\",\"created_at\":\"2024-08-09 20:53:46\",\"extension\":\"png\",\"order_by\":3,\"title\":\"Figure 3\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":121703,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eCostello graph. Prey-specific abundance vs. frequency of occurrence the diet of northern pike, \\u003cem\\u003eEsox lucius\\u003c/em\\u003e\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Fig3.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4656714/v1/ae4426a22d2918d050b598fe.png\"},{\"id\":62154936,\"identity\":\"42494e83-1b51-4b94-9b24-8e5e4654e546\",\"added_by\":\"auto\",\"created_at\":\"2024-08-09 21:01:46\",\"extension\":\"png\",\"order_by\":4,\"title\":\"Figure 4\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":160131,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003ePearre’s selectivity index of the prey fishes in Sıddıklı Dam Lake. *Significant at p \\u0026lt; 0.05 in the \\u003cem\\u003ex\\u003c/em\\u003e\\u003csup\\u003e2\\u003c/sup\\u003e-test.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Fig4.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4656714/v1/45306d2474eea1f5d46aebd4.png\"},{\"id\":62157383,\"identity\":\"83e2babd-5bee-4403-80d9-633d8a51a524\",\"added_by\":\"auto\",\"created_at\":\"2024-08-09 21:17:51\",\"extension\":\"pdf\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"manuscript-pdf\",\"size\":1184263,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"manuscript.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4656714/v1/8f925a41-8ed8-4f31-9980-9126911c2a24.pdf\"}],\"financialInterests\":\"No competing interests reported.\",\"formattedTitle\":\"Diet and Feeding Strategy of Northern Pike, Esox lucius L., 1758 Inhabiting A Deep Dam Lake from Located Central Anatolia, TÜRKİYE\",\"fulltext\":[{\"header\":\"Introduction\",\"content\":\"\\u003cp\\u003ePiscivorous fishes are typically considered the most influential top predator or keystone within aquatic ecosystems. These fishes directly and indirectly influence species occupying lower trophic levels and create top-down trophic cascades impacting the entire food-web. Also, aquatic keystone predators that the top level of the food web (piscivorous fish) may have strong effects on the structure, function, and biodiversity of aquatic habitats such as freshwater and coastal ecosystems (Nilsson et al. \\u003cspan citationid=\\\"CR33\\\" class=\\\"CitationRef\\\"\\u003e2023\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eNorthern pike (\\u003cem\\u003eEsox lucius\\u003c/em\\u003e) is a widely distributed freshwater fish in the northern hemisphere (Craig \\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e), and it has commercial value in T\\u0026uuml;rkiye (Yazicioglu et al. \\u003cspan citationid=\\\"CR47\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e), also to be used for recreational fisheries in different areas of world (Didenko and Gurbyk \\u003cspan citationid=\\\"CR13\\\" class=\\\"CitationRef\\\"\\u003e2016\\u003c/span\\u003e; Trella and Woƚos \\u003cspan citationid=\\\"CR41\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e). The northern pike is an important keystone piscivore in many aquatic ecosystems (Kek\\u0026auml;l\\u0026auml;inen et al. \\u003cspan citationid=\\\"CR25\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e) and a top-level predator in aquatic food chains in the northern hemisphere (Winfield et al. \\u003cspan citationid=\\\"CR43\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e). It has a significant influence on the species composition, density, distribution, and structure of the fish populations inhabiting different aquatic habitats (Craig \\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e). Pike is a predator that attacks from ambush and spends less energy for catching, handling, and swallowing of the prey (Nilsson and Br\\u0026ouml;nmark \\u003cspan citationid=\\\"CR32\\\" class=\\\"CitationRef\\\"\\u003e1999\\u003c/span\\u003e). Pike prefer shallow vegetated and low-flow habitats. Because northern pike needs these habitats where can hide and ambush its prey (Casselman and Lewis \\u003cspan citationid=\\\"CR7\\\" class=\\\"CitationRef\\\"\\u003e1996\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eScientific knowledge on food and feeding habits of fish is both an important condition for increasing fish production (Malik et al. \\u003cspan citationid=\\\"CR29\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e) and important for evaluating the ecological role and position of the species in the food web of ecosystems (Saikia \\u003cspan citationid=\\\"CR38\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e). Besides, Knowledge of the food habits and diets of a fish species is important to understanding many aspects of fish biology, physiology, and behavior. Food and feeding habits of the fishes be affected throughout the day, season, body size, habitat, environmental condition, and food sources available (Malik et al. \\u003cspan citationid=\\\"CR29\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e). Therefore, evaluating nutritional studies according to these basic factors is very important in terms of fish biology and fisheries management.\\u003c/p\\u003e \\u003cp\\u003eInformation on the feeding features of top predator or piscivorous species, such as diet composition, feeding habits, and feeding strategy, is useful to assess the role of freshwater fishes in the ecosystem. Information obtained from feeding studies can be used for sustainable fisheries management and protection of aquatic ecosystems. The main objective of this study was to comparatively describe the seasonal variations in diet composition, and feeding features such as feeding habits and strategy, and food preferences of top predator northern pike.\\u003c/p\\u003e\"},{\"header\":\"Material and Method\",\"content\":\"\\u003cdiv id=\\\"Sec3\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eStudy Area and Sampling\\u003c/h2\\u003e \\u003cp\\u003eSıddıklı K\\u0026uuml;\\u0026ccedil;\\u0026uuml;kboğaz Dam Lake (formerly called Karababa Dam) is a zonal dam on K\\u0026ouml;rpeli Boğaz Creek at the border of the Province of Kırşehir located from Central Anatolian region of T\\u0026uuml;rkiye. This dam lake is composed of clay and rock, with a central core. Dam construction began in 1991 and was finished in 2002. The lake dam is made of clay and filled with rock. It has a 1.62 km\\u003csup\\u003e2\\u003c/sup\\u003e surface area with an active water level of 25.3 hm\\u003csup\\u003e3\\u003c/sup\\u003e (Akkan et al. \\u003cspan citationid=\\\"CR2\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e). Pike gill nets were simultaneously used to collect fish samples monthly from September 2015 to August 2016 at Sıddıklı K\\u0026uuml;\\u0026ccedil;\\u0026uuml;kboğaz Dam Lake. The nets were set at dusk, left in the water for 12-hour min, and hauled at 08:00\\u0026ndash;09:00 h. The nets were composed of pelagic gill nets with bar mesh sizes (knot to knot) of 20, 25, 30, 35, 40, 45, 55, 65, and 80 mm. All operations on fish capture and dead fish studied in the laboratory were carried out in accordance with animal health and welfare ethical rules. This study was approved by the animal experiments local ethics committee (document no: 68429034/05). Additionally, our study complies with ARRIVE 2.0 guidelines. Some physical and chemical parameters of the lake water, such as dissolved oxygen (DO), temperature, salinity, pH, conductivity, total dissolved solid (TDS) were measured monthly from September 2015 to August 2016 (Yazıcı \\u003cspan citationid=\\\"CR44\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e) and environmental variables were given Table\\u0026nbsp;\\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e.\\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\\u003eMonthly changes in some physicochemical parameters of surface water in Sıddıklı Dam Lake from September 2015 to August 2016\\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=\\\"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 \\u003cthead\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\" morerows=\\\"1\\\" rowspan=\\\"2\\\"\\u003e \\u003cp\\u003eMonths\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colspan=\\\"6\\\" nameend=\\\"c7\\\" namest=\\\"c2\\\"\\u003e \\u003cp\\u003eWater Parameters\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eTemperature\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003epH\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003eDO\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003eSalinity\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003eTDS\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003eConductivity\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003c/thead\\u003e \\u003ctbody\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eSeptember 2015\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e22.91\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e8.22\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e9.38\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.48\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e6.63\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e940.00\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eOctober\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e15.77\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e7.51\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e14.90\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.52\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e6.73\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e850.00\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eNovember\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e10.40\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e8.41\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e7.16\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.78\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e9.95\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e1100.00\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eDecember\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e3.68\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e8.41\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e11.03\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.63\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e8.29\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e750.00\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eJanuary 2016\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e3.10\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e8.21\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e11.79\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.40\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e5.35\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e820.00\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eFebruary\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e7.40\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e8.15\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e11.76\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.44\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e5.77\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e890.00\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eMarch\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e8.78\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e8.25\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e9.24\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.35\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e4.55\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e700.00\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eApril\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e14.93\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e8.16\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e8.79\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.34\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e4.48\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e690.00\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eMay\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e18.10\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e8.31\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e7.18\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.34\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e4.52\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e700.00\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eJune\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e20.85\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e8.40\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e6.86\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.32\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e4.28\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e650.00\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eJuly\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e24.48\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e8.31\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e6.02\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.33\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e4.42\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e680.00\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eAugust\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e23.05\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e8.37\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e5.97\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.33\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e4.72\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e700.00\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003c/tbody\\u003e \\u003c/colgroup\\u003e \\u003c/table\\u003e\\u003c/div\\u003e \\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec4\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eLaboratory Methods and Stomach Content Analysis\\u003c/h2\\u003e \\u003cp\\u003eA total of one hundred thirty-three (133) samples were examined for stomach analysis. In the laboratory, all fish samples were measured in cm (total length) and weighed in grams. The stomachs were removed by dissection from each specimen and preserved in a 4% formaldehyde solution for afterward analysis. The stomachs were opened during the examination, and the prey was identified, weighed in grams, sorted, and classified to the lowest taxonomic level before being preserved in 70% ethanol. Also, full and empty stomach weights were measured with a precision of 0.01 g. When a prey item was mostly digested, identification of prey fishes was based on scales, pharyngeal bones (cyprinids), opercular bones, vertebrae, and the location of the mouth and eyes (Pavlović et al. \\u003cspan citationid=\\\"CR35\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eTo compare the change of feeding intensity between seasons the fullness index (FI\\u0026thinsp;=\\u0026thinsp;weight of stomach content/ weight of fish *100) and the vacuity index (VI%= the number of empty stomachs/total number of the examined stomachs* 100) were calculated (De Santis and Volta \\u003cspan citationid=\\\"CR12\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e). Low feeding activity is considered when high vacuity index is observed (Martinho et al., \\u003cspan citationid=\\\"CR30\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e). Kruskal-Wallis test (K-W test) was used to analyze whether seasons affected the fullness index (FI) in northern pike. Spearman\\u0026rsquo;s rank correlation was used to determine the relationship between fullness index (FI) and physicochemical parameters of surface water. Also, A chi-square test (χ2) was applied to determine the vacuity index (%VI) changes between the seasons.\\u003c/p\\u003e \\u003cp\\u003eTraditional methods such as percentage frequency of occurrence (FO%= number of stomachs containing prey i/number of stomachs with any food item* 100), numerical percentage (N%= number of prey i/total number of all prey items* 100), and percentage by weight (W%= weight of prey i/total weight of all prey items* 100) of dietary analysis were used to determine feeding features (Hyslop \\u003cspan citationid=\\\"CR21\\\" class=\\\"CitationRef\\\"\\u003e1980\\u003c/span\\u003e). The main food items were identified using index of relative importance (IRI) of Pinkas et al. (\\u003cspan citationid=\\\"CR37\\\" class=\\\"CitationRef\\\"\\u003e1971\\u003c/span\\u003e), as modified by Hacunda (\\u003cspan citationid=\\\"CR18\\\" class=\\\"CitationRef\\\"\\u003e1981\\u003c/span\\u003e).\\u003cdiv id=\\\"Equa\\\" class=\\\"Equation\\\"\\u003e\\u003cdiv format=\\\"TEX\\\" class=\\\"mathdisplay\\\" id=\\\"FileID_Equa\\\" name=\\\"EquationSource\\\"\\u003e\\n$$\\\\:IRI=\\\\left(\\\\%N+\\\\%W\\\\right)\\\\times\\\\:\\\\%FO$$\\u003c/div\\u003e\\u003c/div\\u003e\\u003c/p\\u003e \\u003cp\\u003eThis index has been expressed as the percentage of each prey item;\\u003cdiv id=\\\"Equb\\\" class=\\\"Equation\\\"\\u003e\\u003cdiv format=\\\"TEX\\\" class=\\\"mathdisplay\\\" id=\\\"FileID_Equb\\\" name=\\\"EquationSource\\\"\\u003e\\n$$\\\\:\\\\%IRI=\\\\left(IRI/\\\\sum\\\\:IRI\\\\right)x\\\\:100$$\\u003c/div\\u003e\\u003c/div\\u003e\\u003c/p\\u003e \\u003cp\\u003eFor computation of the relative amounts of intraspecific competition between seasons, simplified Morisita-Horn index (C\\u003csub\\u003eh\\u003c/sub\\u003e) based on %N data was used (Horn \\u003cspan citationid=\\\"CR20\\\" class=\\\"CitationRef\\\"\\u003e1966\\u003c/span\\u003e):\\u003cdiv id=\\\"Equc\\\" class=\\\"Equation\\\"\\u003e\\u003cdiv format=\\\"TEX\\\" class=\\\"mathdisplay\\\" id=\\\"FileID_Equc\\\" name=\\\"EquationSource\\\"\\u003e\\n$$\\\\:{C}_{h}=\\\\frac{2\\\\:\\\\left(\\\\sum\\\\:{p}_{ij}{p}_{ik}\\\\right)}{\\\\sum\\\\:{p}_{ij}^{2}+\\\\sum\\\\:{p}_{ik}^{2}}$$\\u003c/div\\u003e\\u003c/div\\u003e\\u003c/p\\u003e \\u003cp\\u003ewhere C\\u003csub\\u003eh\\u003c/sub\\u003e is the Morisita-Horn index of diet overlap between different seasons p\\u003csub\\u003eij\\u003c/sub\\u003e is the proportion of food type \\u0026ldquo;i\\u0026rdquo; f the total food quantity by seasons \\u0026ldquo;j,\\u0026rdquo; p\\u003csub\\u003eik\\u003c/sub\\u003e is the proportion of food type \\u0026ldquo;i\\u0026rdquo; of the total food used by seasons \\u0026ldquo;k\\u0026rdquo; and, n is the total number of food types. The degree of overlap was classified as low (0.0\\u0026ndash;0.29), moderate (0.30\\u0026ndash;0.59), and high (0.60\\u0026ndash;1.00) (Langton \\u003cspan citationid=\\\"CR26\\\" class=\\\"CitationRef\\\"\\u003e1982\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eThe selectivity of prey categories in the diet was statistically tested with x\\u003csup\\u003e2\\u003c/sup\\u003e-test, utilizing Pearre's C index of prey selection. The index value (\\u003cem\\u003eVa\\u003c/em\\u003e) varies from \\u0026minus;\\u0026thinsp;1 (prey avoidance) to +\\u0026thinsp;1 (prey selection), with 0 indicating random prey selection (Pearre \\u003cspan citationid=\\\"CR36\\\" class=\\\"CitationRef\\\"\\u003e1982\\u003c/span\\u003e).\\u003cdiv id=\\\"Equd\\\" class=\\\"Equation\\\"\\u003e\\u003cdiv format=\\\"TEX\\\" class=\\\"mathdisplay\\\" id=\\\"FileID_Equd\\\" name=\\\"EquationSource\\\"\\u003e\\n$$\\\\:Va=\\\\frac{({a}_{d}\\\\times\\\\:{b}_{e})-({a}_{e}\\\\times\\\\:{b}_{d})}{\\\\sqrt{a\\\\times\\\\:b\\\\times\\\\:d\\\\times\\\\:e}}$$\\u003c/div\\u003e\\u003c/div\\u003e\\u003c/p\\u003e \\u003cp\\u003ewhere \\u003cem\\u003eVa\\u003c/em\\u003e is Pearre\\u0026rsquo;s index for pike selection of prey a, \\u003cem\\u003ead\\u003c/em\\u003e is the abundance of prey a in the diet, \\u003cem\\u003ebe\\u003c/em\\u003e is the abundance of all other prey in the environment, \\u003cem\\u003ebd\\u003c/em\\u003e is the abundance of all other prey in the diet, and \\u003cem\\u003eae\\u003c/em\\u003e is the abundance of prey a in the environment.\\u003c/p\\u003e \\u003cp\\u003eValues without subscripts are expressed as follows:\\u003cdiv id=\\\"Eque\\\" class=\\\"Equation\\\"\\u003e\\u003cdiv format=\\\"TEX\\\" class=\\\"mathdisplay\\\" id=\\\"FileID_Eque\\\" name=\\\"EquationSource\\\"\\u003e\\n$$\\\\:a={a}_{d}+{a}_{e}$$\\u003c/div\\u003e\\u003c/div\\u003e\\u003cdiv id=\\\"Equf\\\" class=\\\"Equation\\\"\\u003e\\u003cdiv format=\\\"TEX\\\" class=\\\"mathdisplay\\\" id=\\\"FileID_Equf\\\" name=\\\"EquationSource\\\"\\u003e\\n$$\\\\:b={b}_{d}+{b}_{e}$$\\u003c/div\\u003e\\u003c/div\\u003e\\u003cdiv id=\\\"Equg\\\" class=\\\"Equation\\\"\\u003e\\u003cdiv format=\\\"TEX\\\" class=\\\"mathdisplay\\\" id=\\\"FileID_Equg\\\" name=\\\"EquationSource\\\"\\u003e\\n$$\\\\:d={a}_{d}+{b}_{d}$$\\u003c/div\\u003e\\u003c/div\\u003e\\u003cdiv id=\\\"Equh\\\" class=\\\"Equation\\\"\\u003e\\u003cdiv format=\\\"TEX\\\" class=\\\"mathdisplay\\\" id=\\\"FileID_Equh\\\" name=\\\"EquationSource\\\"\\u003e\\n$$\\\\:e={a}_{e}+{b}_{e}$$\\u003c/div\\u003e\\u003c/div\\u003e\\u003c/p\\u003e \\u003cp\\u003eThe statistical significance of the selection index value (\\u003cem\\u003eVa\\u003c/em\\u003e) was tested using the chi-squared test.\\u003cdiv id=\\\"Equi\\\" class=\\\"Equation\\\"\\u003e\\u003cdiv format=\\\"TEX\\\" class=\\\"mathdisplay\\\" id=\\\"FileID_Equi\\\" name=\\\"EquationSource\\\"\\u003e\\n$$\\\\:{x}^{2}=n\\\\times\\\\:{C}^{2}$$\\u003c/div\\u003e\\u003c/div\\u003e\\u003c/p\\u003e \\u003cp\\u003eThe value of relative abundance (ae) used in the prey selection index for each fish species inhabiting Sıddıklı Dam Lake was obtained from Yazıcı (\\u003cspan citationid=\\\"CR44\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eFeeding strategy was determined from the plot of percentages of prey-specific abundance (Pi%) against frequency of occurrence (FO). Prey specific abundance, the percent numerical abundance of a prey item averaged over the stomach samples in which it occurs, was calculated using the methodology in Amundsen et al. (\\u003cspan citationid=\\\"CR4\\\" class=\\\"CitationRef\\\"\\u003e1996\\u003c/span\\u003e).\\u003cdiv id=\\\"Equj\\\" class=\\\"Equation\\\"\\u003e\\u003cdiv format=\\\"TEX\\\" class=\\\"mathdisplay\\\" id=\\\"FileID_Equj\\\" name=\\\"EquationSource\\\"\\u003e\\n$$\\\\:Pi=\\\\left(\\\\frac{\\\\sum\\\\:Si}{\\\\sum\\\\:Sti}\\\\right)*100$$\\u003c/div\\u003e\\u003c/div\\u003e\\u003c/p\\u003e \\u003cp\\u003ewhere Pi\\u0026thinsp;=\\u0026thinsp;Prey specific abundance of prey i; Si\\u0026thinsp;=\\u0026thinsp;Abundance of prey in stomachs and Sti\\u0026thinsp;=\\u0026thinsp;Total abundance of prey in predators that contain prey i. For specialist feeding, prey items appear in the upper part of the plot, while generalists have all prey points in the lower part.\\u003c/p\\u003e \\u003c/div\\u003e\"},{\"header\":\"Results\",\"content\":\"\\u003cp\\u003eDuring this study, 133 specimens of \\u003cem\\u003eEsox lucuis\\u003c/em\\u003e were collected. Of these, 73 specimen (54.9%) had food item, while 60 (45.1%) had empty stomachs.\\u003c/p\\u003e \\u003cp\\u003eThe feeding intensity of \\u003cem\\u003eE. lucius\\u003c/em\\u003e according to season was shown in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e. The vacuity index (VI%) was highest during winter (49.2%) and lowest during summer (28.6%) (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e). VI% values did not reveal significant differences between seasons (x\\u003csup\\u003e2\\u003c/sup\\u003e\\u0026thinsp;=\\u0026thinsp;2.832, p\\u0026thinsp;\\u0026gt;\\u0026thinsp;0.05). The fullness index which is a real indicator for feeding intensity exhibited the highest values during Summer (FI\\u0026thinsp;=\\u0026thinsp;1.59) and Autumn (FI\\u0026thinsp;=\\u0026thinsp;1.13), while the lowest values were during winter (FI\\u0026thinsp;=\\u0026thinsp;0.51) and Spring (FI\\u0026thinsp;=\\u0026thinsp;1.07) (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e). The change between seasons in the vacuity index was not found to be statistically significant. (K-W test, p\\u0026thinsp;\\u0026gt;\\u0026thinsp;0.05).\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003eSpearman rank correlation analysis indicated that there was a positive correlation between fullness index (FI) and temperature (rs\\u0026thinsp;=\\u0026thinsp;0.117), pH (rs\\u0026thinsp;=\\u0026thinsp;0.05), total dissolved solid (TDS) (rs\\u0026thinsp;=\\u0026thinsp;0.061), and conductivity (rs\\u0026thinsp;=\\u0026thinsp;0.064), but not statistically significant (p\\u0026thinsp;\\u0026gt;\\u0026thinsp;0.05). The negative correlation between fullness index (FI) and dissolved oxygen (rs = -0.058) and salinity (rs = -0.173) was detected. The differences were statistically significant in the salinity parameter (p\\u0026thinsp;\\u0026lt;\\u0026thinsp;0.05), while differences were not statistically significant in the dissolved oxygen parameter (p\\u0026thinsp;\\u0026gt;\\u0026thinsp;0.05).\\u003c/p\\u003e \\u003cdiv id=\\\"Sec6\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eGeneral diet composition\\u003c/h2\\u003e \\u003cp\\u003eThe diet of pike comprised six (6) food items, containing only prey fish species. The diet of 73 pike samples included 116 prey items, comprising \\u003cem\\u003eTinca tinca\\u003c/em\\u003e (52), \\u003cem\\u003eAtherina boyeri\\u003c/em\\u003e (40), \\u003cem\\u003eCyprinus carpio\\u003c/em\\u003e (8), \\u003cem\\u003eSqualius seyhanensis\\u003c/em\\u003e (8), \\u003cem\\u003eAlburnus orontis\\u003c/em\\u003e (5) and, unidentified fish (3). (Table\\u0026nbsp;\\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e). \\u003cem\\u003eT. tinca\\u003c/em\\u003e was the dominant prey in number with 44.83%, followed by \\u003cem\\u003eA. boyeri\\u003c/em\\u003e (N\\u0026thinsp;=\\u0026thinsp;34.48%). The frequency of occurrence of \\u003cem\\u003eT. tinca\\u003c/em\\u003e was the highest (56.16%), followed by \\u003cem\\u003eA. boyeri\\u003c/em\\u003e (27.4%). The total wet weight of 116 prey items was 675.88 g. \\u003cem\\u003eT. tinca\\u003c/em\\u003e was the most frequently consumed prey item with 66.68% by weight, followed by \\u003cem\\u003eS. seyhanensis\\u003c/em\\u003e with 15.7%. According to the relative importance index (IRI), the most important food items was \\u003cem\\u003eT. tinca\\u003c/em\\u003e (79.51%), followed by \\u003cem\\u003eA. boyeri\\u003c/em\\u003e (14.8%) (Table\\u0026nbsp;\\u003cspan refid=\\\"Tab2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\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\\u003eGeneral diet composition of pike (\\u003cem\\u003eEsox lucius\\u003c/em\\u003e) in Sıddıklı K\\u0026uuml;\\u0026ccedil;\\u0026uuml;kboğaz Dam Lake. n, prey number; N%, numerical percentage; W, prey weight; W%, percentage by weight; O, frequency of occurrence; FO%, percentage frequency of occurrence; IRI, index of relative importance.\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/caption\\u003e \\u003ccolgroup cols=\\\"9\\\"\\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=\\\"char\\\" char=\\\".\\\" 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=\\\"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=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c9\\\" colnum=\\\"9\\\"\\u003e\\u003c/div\\u003e \\u003cthead\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eFood items\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003en\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eN%\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003eW\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003eW%\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003eO\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003eFO%\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003eIRI\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003eIRI%\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003c/thead\\u003e \\u003ctbody\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eT.tinca\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e52\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e44.83\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e450.66\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e66.68\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e41\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e56.16\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e6262.402\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e79.51\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eA. boyeri\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e40\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e34.48\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e54.41\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e8.05\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e20\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e27.4\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e1165.322\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e14.80\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eC. carpio\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e8\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e6.9\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e36.2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e5.35\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e8\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e10.96\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e134.26\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e1.70\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eS. seyhanensis\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e8\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e6.9\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e106.08\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e15.7\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e8\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e10.96\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e247.696\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e3.14\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eA. orontis\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e4.3\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e13.38\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e1.98\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e6.85\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e43.018\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e0.55\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eUnidentified fish\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e3\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e2.59\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e6.12\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.91\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e3\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e4.11\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e14.385\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e0.18\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eFish remains\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e-\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e-\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e9.03\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e1.33\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e6.85\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e9.1105\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e0.12\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eToplam\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e116\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e100\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e675.88\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e100\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c7\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e7876.193\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e100\\u003c/b\\u003e\\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\\u003eThere was a little seasonal variation in food habits of \\u003cem\\u003eEsox lucius\\u003c/em\\u003e in studied area (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e). \\u003cem\\u003eT.tinca\\u003c/em\\u003e were the dominant prey group during all seasons, particularly from spring (IRI %= 79.71) to summer (IRI% = 80.28). \\u003cem\\u003eA. boyeri\\u003c/em\\u003e and \\u003cem\\u003eS. seyhanensis\\u003c/em\\u003e were also present in the diet throughout the year, with a peak value recorded in winter (IRI %= 27.38) and spring (IRI%= 9.39) respectively. \\u003cem\\u003eC. carpio\\u003c/em\\u003e were present in contents during all seasons except autumn, while \\u003cem\\u003eA. orontis\\u003c/em\\u003e were only found in autumn. These prey items were observed smaller quantities in diet. Morisita-Horn index showed a high degree of dietary overlap between seasons, ranging from 0.7754 to 0.9675 (Table\\u0026nbsp;\\u003cspan refid=\\\"Tab3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e). These overlap values indicated that fishes fed on similar food items when living in this habitat throughout the year. It was show that the least of diet similarity (0.7754) was in autumn-winter. In contrast, the food of northern pike showed an extreme high dietary overlap (0.9675%) in spring-summer.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003e \\u003cdiv class=\\\"gridtable\\\"\\u003e\\u003ctable float=\\\"Yes\\\" id=\\\"Tab3\\\" border=\\\"1\\\"\\u003e \\u003ccaption language=\\\"En\\\"\\u003e \\u003cdiv class=\\\"CaptionNumber\\\"\\u003eTable 3\\u003c/div\\u003e \\u003cdiv class=\\\"CaptionContent\\\"\\u003e \\u003cp\\u003eResults of Morisita-Horn indices for the diets overlap between seasons in northern pike.\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/caption\\u003e \\u003ccolgroup cols=\\\"5\\\"\\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 \\u003cthead\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eC\\u003csub\\u003eh\\u003c/sub\\u003e\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eSpring\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eSummer\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003eAutumn\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003eWinter\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003c/thead\\u003e \\u003ctbody\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eSpring\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e-\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eSummer\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e0.9675*\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e-\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eAutumn\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e0.8820*\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e0.8705*\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e-\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eWinter\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e0.8840*\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e0.9657*\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e0.7754*\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e-\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003c/tbody\\u003e \\u003c/colgroup\\u003e \\u003ctfoot\\u003e \\u003ctr\\u003e\\u003ctd colspan=\\\"5\\\"\\u003e* Statistically significant\\u003c/td\\u003e\\u003c/tr\\u003e \\u003c/tfoot\\u003e \\u003c/table\\u003e\\u003c/div\\u003e \\u003c/p\\u003e \\u003cp\\u003eThe dietary pattern of \\u003cem\\u003eEsox lucius\\u003c/em\\u003e is graphically showed in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e where the prey-specific abundance (Pi) is plotted against the frequency of occurrence (FO%). The feeding strategy of the northern pike showed variety for prey items. The diet of northern pike was mostly based on rare species that were eaten occasionally and in relatively small amounts, such as \\u003cem\\u003eCyprinus carpio\\u003c/em\\u003e, \\u003cem\\u003eSqualius seyhanensis\\u003c/em\\u003e, \\u003cem\\u003eAlburnus orontis\\u003c/em\\u003e and unidentified fish, except for \\u003cem\\u003eTinca tinca\\u003c/em\\u003e and \\u003cem\\u003eAtherina boyeri\\u003c/em\\u003e, which tended to be dominant prey. The population of the northern pike can be considered as a generalist predator with a relatively broad niche width, hovewer population consists of some specialized individuals that feed widely on \\u003cem\\u003eT. tinca\\u003c/em\\u003e (i.e., prey with a high prey-specific abundance and more than 50% frequency of occurrence) and \\u003cem\\u003eA. boyeri\\u003c/em\\u003e (i.e., prey with a high prey-specific abundance and less than 40% frequency of occurrence). \\u003cem\\u003eT. tinca\\u003c/em\\u003e and \\u003cem\\u003eA. boyeri\\u003c/em\\u003e were located in the upper middle part of the diagram, and this situation demonstrated the importance of these prey items in the diet of northern pike, as well as a trend toward population specialization regarding this prey. These specialized fish shift the feeding strategy of northern pike towards a higher between-phenotype contribution to the utilization of the resource gradient or niche width (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e). In other words, for a generalist predator like \\u003cem\\u003eE. lucius\\u003c/em\\u003e, the sharing of food resources is ensured by certain individuals who specialize in consuming limited but plentiful prey.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003eAccording to the prey selection index (C), there was positive selection for \\u003cem\\u003eTinca tinca\\u003c/em\\u003e (C\\u0026thinsp;=\\u0026thinsp;0.5233) and \\u003cem\\u003eAlburnus orontis\\u003c/em\\u003e (C\\u0026thinsp;=\\u0026thinsp;0.1114), negative selection for \\u003cem\\u003eCyprinus c\\u003c/em\\u003earpio (C= -0.1193) and \\u003cem\\u003eSqualius seyhanensis\\u003c/em\\u003e (C= -0.02523), and close to neutral selection for \\u003cem\\u003eAtherina boyeri\\u003c/em\\u003e (C\\u0026thinsp;=\\u0026thinsp;0.009478) by pike individuals. Estimated prey selection indices of the prey fish were statistically insignificant (P\\u0026thinsp;\\u0026gt;\\u0026thinsp;0.05), except \\u003cem\\u003eT.tinca\\u003c/em\\u003e (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig4\\\" class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003c/div\\u003e\"},{\"header\":\"Discussion\",\"content\":\"\\u003cp\\u003eThis study provided information on the food items and feeding habits of \\u003cem\\u003eEsox lucius\\u003c/em\\u003e, a predatory fish species caught from Sıddıklı Dam Lake in T\\u0026uuml;rkiye Inland Water. During the study, 73 (64.9%) specimens had food items in their stomach while 60 (45.1%) individuals possessed empty. It was found that the empty stomach rate (VI%) of pike varied between 10.24% and 77% in studies conducted in different habitats (Soupir et al., \\u003cspan citationid=\\\"CR40\\\" class=\\\"CitationRef\\\"\\u003e2000\\u003c/span\\u003e; Yılmaz and Polat \\u003cspan citationid=\\\"CR49\\\" class=\\\"CitationRef\\\"\\u003e2005\\u003c/span\\u003e; Alp et al. \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; Yılmaz et al. 2010; Yazicioglu et al. \\u003cspan citationid=\\\"CR47\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e). Chapman et al. (\\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e1989\\u003c/span\\u003e) reported that the proportion of empty stomachs in northern pike is positively related to the frequency of occurrence of prey fish in stomach. Arrington et al. (\\u003cspan citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e2002\\u003c/span\\u003e) stated that the presence of a high percentage of empty stomach is a common situation in piscivorous fish. Similarly, the value of VI expressed as the percentage of empty stomachs was high in study area and it was generally consistent with the results of previous studies (Kangur andKangur \\u003cspan citationid=\\\"CR24\\\" class=\\\"CitationRef\\\"\\u003e1998\\u003c/span\\u003e; Didenko and Gurbyk \\u003cspan citationid=\\\"CR13\\\" class=\\\"CitationRef\\\"\\u003e2016\\u003c/span\\u003e). Most empty stomachs are probably related to nets stay time of fish and the digestive process after the fish are caught. The high rate of empty stomachs may also be due to the sampling method (gill nets) that causes predator fish to vomit their stomach contents (Didenko and Gurbyk \\u003cspan citationid=\\\"CR13\\\" class=\\\"CitationRef\\\"\\u003e2016\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eOur findings showed that the values of the fullness index (FI) follow an inverse trend to vacuity index values (VI%). This finding is consistent with results for previous studies in different species or habitats (Giarrizzo and Saint-Paul \\u003cspan citationid=\\\"CR16\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; Yazicioglu et al. \\u003cspan citationid=\\\"CR47\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e). The vacuity index (VI) is an inverse indication of feeding intensity which vary according to variations in the spawning time (Yazıcıoğlu et al. \\u003cspan citationid=\\\"CR46\\\" class=\\\"CitationRef\\\"\\u003e2016\\u003c/span\\u003e), seasonal changes in water temperature (Okgerman et al. \\u003cspan citationid=\\\"CR34\\\" class=\\\"CitationRef\\\"\\u003e2013\\u003c/span\\u003e) and food item (Yazicioglu et al. \\u003cspan citationid=\\\"CR47\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e). Seasonal variations in feeding intensity show an increase in the fullness index during summer while, this index be detected a decrease in the winter in this study. Similarly, Bregazzi and Kenndy (1980) determined that feeding increased in summer and autumn, with less intensive feeding during the spawning season and in winter. Alp et al. (\\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e) reported that the percentage of empty stomachs of this species in \\u0026Ccedil;ivril Lake was highest in winter and that it fed more intensively during the spring and summer seasons. Reason of lower feeding intensity in winter is most likely due to lower water temperatures which slow down metabolism. Similar to the results of our study, the main environmental factor affecting feeding intensity of fishes is water temperature (Okgerman et al. \\u003cspan citationid=\\\"CR34\\\" class=\\\"CitationRef\\\"\\u003e2013\\u003c/span\\u003e; Yazicioglu et al. 2022).\\u003c/p\\u003e \\u003cp\\u003eNorthern pike consumed a narrow range of prey items in this study and their diet consisted of only prey fishes. The northern pike exhibited piscivorous feeding features in this area, and the present results are similar to the finding of Liao et al. (\\u003cspan citationid=\\\"CR27\\\" class=\\\"CitationRef\\\"\\u003e2002\\u003c/span\\u003e) in Spirit Lake (Iowa, USA), Yilmaz et al. (\\u003cspan citationid=\\\"CR48\\\" class=\\\"CitationRef\\\"\\u003e2010\\u003c/span\\u003e) in Lake Uluabat (Bursa, T\\u0026uuml;rkiye), Yılmaz and Enver (2014) in Sıdıklı Dam Lake (Kırşehir, T\\u0026uuml;rkiye), and Pavlović et al (\\u003cspan citationid=\\\"CR35\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e) in Šumarice Reservoir (Serbia). It is thought that the consumption of only fish species in the study is due to the size distribution of the studied samples and the larger body size of food fish compared to benthic invertebrates. Additionally, feeding exclusively on fish may be due to the small surface area of the aquatic habitat studied and the high fish density. However, previous studies reported that this species displayed a highly diversified diet and consumed a broad range of prey items from invertebrate to vertebrate (Soupir et al. \\u003cspan citationid=\\\"CR40\\\" class=\\\"CitationRef\\\"\\u003e2000\\u003c/span\\u003e; Alp et al. \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; Yazicioglu et al. \\u003cspan citationid=\\\"CR47\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e; Cathcart et al. \\u003cspan citationid=\\\"CR8\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e). In this study, a total of five different food fish were detected in the stomach of the pike and the most important prey fishes were \\u003cem\\u003eT. tinca\\u003c/em\\u003e and \\u003cem\\u003eA. boyeri\\u003c/em\\u003e, respectively. M\\u0026ecirc;rő (\\u003cspan citationid=\\\"CR31\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e) reported that a total of 51 prey-fish species were observed in the stomachs of pike in different studies. The differences of prey fishes in diet composition are mainly due to availability of prey items in different habitats. Cannibalism detected generally in northern pike populations (Alp et al. \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; Cathcart et al. \\u003cspan citationid=\\\"CR8\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e), however intraspecific predation (cannibalism) did not occur in the northern pike population in this study. Other researchers also not observed cannibalism among northern pike in different freshwater ecosystems (Yilmaz et al. \\u003cspan citationid=\\\"CR48\\\" class=\\\"CitationRef\\\"\\u003e2010\\u003c/span\\u003e; Pavlović et al. \\u003cspan citationid=\\\"CR35\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e; Jacobson et al. \\u003cspan citationid=\\\"CR22\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e). The reason for the absence of cannibalism is due to the abundance of prey fishes in the lake and the low density of predator species. Furthermore, Craig (\\u003cspan citationid=\\\"CR10\\\" class=\\\"CitationRef\\\"\\u003e1996\\u003c/span\\u003e) found that the occurrence of cannibalism varied according on the availability of prey fish and pike density.\\u003c/p\\u003e \\u003cp\\u003eThe feeding habits of pike and their predation on fish showed little change depending on the seasons. The most consumed food in all seasons was \\u003cem\\u003eT. tinca\\u003c/em\\u003e, followed by \\u003cem\\u003eA. boyeri\\u003c/em\\u003e and \\u003cem\\u003eS. seyhanensis\\u003c/em\\u003e, respectively. Many studies have stated that there are seasonal changes in the diet of pike (Liao et al. \\u003cspan citationid=\\\"CR27\\\" class=\\\"CitationRef\\\"\\u003e2002\\u003c/span\\u003e; Alp et al. \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e). The seasonal variations in diet can be associated to the density, abundance, and availability of prey items.\\u003c/p\\u003e \\u003cp\\u003eThe results of this study showed that some of the analyzed specimens specialized on certain types of prey fish, whereas the entire sample seems to have a generalized feeding strategy. This feeding strategy can be deduced from the fact that a few prey items have a high prey-specific abundance (%Pi) and a low frequency of occurrence. The generalist feeding strategy of the northern pike is likely associated with the fact that the pike is an opportunistic feeder (Sandlund et al. \\u003cspan citationid=\\\"CR39\\\" class=\\\"CitationRef\\\"\\u003e2016\\u003c/span\\u003e) and can shift prey consumed depending on prey availability (including behavior) and abundance (Craig \\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e). The northern pike some individuals tended to exhibit a specialist feeding strategy towards \\u003cem\\u003eT. tinca\\u003c/em\\u003e and \\u003cem\\u003eA. boyeri\\u003c/em\\u003e in all seasons, while other prey fishes had low prey-specific abundance and were generally rare prey for pike with generalist feeding strategies. Pike exhibited a similar feeding strategy in The Natural Park of the Ruidera Lakes. This species showed a specialized feeding strategy towards crayfish, but a generalized strategy towards other food items (Elvira et al. \\u003cspan citationid=\\\"CR15\\\" class=\\\"CitationRef\\\"\\u003e1996\\u003c/span\\u003e). Cathcart et al. (\\u003cspan citationid=\\\"CR8\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e) indicated that feeding strategies of northern pike inhabiting 31 different waterbodies in Alaska differed among size classes, and generally feeding strategy showed specialization toward vertebrate prey, generalization toward macroinvertebrate prey, except dragonflies. Yazicioglu et al (\\u003cspan citationid=\\\"CR47\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e) reported that changes in feeding features of northern pike living in Ladik Lake depending on size groups (generalist feeding features in small individuals and specialists in large samples).\\u003c/p\\u003e \\u003cp\\u003eIn present study, \\u003cem\\u003eTinca tinca\\u003c/em\\u003e (C\\u0026thinsp;=\\u0026thinsp;0.5233) and \\u003cem\\u003eAlburnus orontis\\u003c/em\\u003e (C\\u0026thinsp;=\\u0026thinsp;0.1114) were the most preferred prey fish. \\u003cem\\u003eCyprinus carpio\\u003c/em\\u003e (C= -0.1193) and \\u003cem\\u003eSqualius seyhanensis\\u003c/em\\u003e were negatively selected by pike. \\u003cem\\u003eA. boyeri\\u003c/em\\u003e, the most abundant species in the lake, is close to neutral selection by pike. Environmental prey abundance was not to shape the prey selection of this fish species in Sıddıklı Dam Lake. Similar results regarding prey preference of northern pike were also reported in \\u0026Ccedil;ivril lake (Alp et al. \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e). Alp et al. (\\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e) reported that \\u003cem\\u003eChondrostoma meandrense, Gobio gobio\\u003c/em\\u003e and \\u003cem\\u003eTinca tinca\\u003c/em\\u003e were the most preferred food species in \\u0026Ccedil;ivril (Denizli) Lake, and \\u003cem\\u003eHemigrammocapoeta kemali\\u003c/em\\u003e and \\u003cem\\u003eAphanius anatolicus\\u003c/em\\u003e were not preferred. The littoral zone of lakes and dam lakes is important for fish species, especially herbivorous and omnivorous species due to protection from predatory fish, breeding, and nesting or shelter. For marine and freshwater ecosystems, aquatic vegetation that supports a varied and abundant fish population is an important biogenic habitat (Akın and Turgut \\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e). Since northern pike are ambush predators that need aquatic vegetation to hide from their prey items, their density is highest in the littoral zone of shallow lotic and lentic ecosystems (Haught and Von Hippel \\u003cspan citationid=\\\"CR19\\\" class=\\\"CitationRef\\\"\\u003e2011\\u003c/span\\u003e). Thus, they can exhibit predation on \\u003cem\\u003eTinca tinca\\u003c/em\\u003e and \\u003cem\\u003eAlburnus orontis\\u003c/em\\u003e that are abundant littoral zone where aquatic plants occur. The fact that carp is not preferred by pike may be due to the high body height of \\u003cem\\u003eC. carpio\\u003c/em\\u003e. Factors such as the soft rays (Ekl\\u0026ouml;v and Hamrin \\u003cspan citationid=\\\"CR14\\\" class=\\\"CitationRef\\\"\\u003e1989\\u003c/span\\u003e; Tyus and Beard \\u003cspan citationid=\\\"CR42\\\" class=\\\"CitationRef\\\"\\u003e1990\\u003c/span\\u003e) and body height (Alp et al. \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e) of the prey fishes play a role in the pike's preference for its prey. Size, shape, and swimming speed of prey, as well as the quantity and quality of prey available and the level of predator satiation and competition a can play a role in the prey's selective by predator. Mouth form and size of predator can be effective in choosing the type and size of food (Juanes et al. \\u003cspan citationid=\\\"CR23\\\" class=\\\"CitationRef\\\"\\u003e2002\\u003c/span\\u003e). Magnhagen and Heibo (\\u003cspan citationid=\\\"CR28\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e) determined that gape size of the predator and the body depth of the prey are the main factors deciding whether a northern pike can ingest a potential prey fish. Pavlović et al. (\\u003cspan citationid=\\\"CR35\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e) reported that northern pike can shift prey preference due to changes in the abundance and vulnerability of prey items in aquatic environments.\\u003c/p\\u003e \\u003cp\\u003eAquatic vegetation provides a significant biogenic habitat for marine and freshwater ecosystems (Akın and Turgut \\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e) and reduces the foraging success of predatory fish by obstructing the vision and attack movements of predators. Therefore, the capture time increase (Gotceitas \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e1990\\u003c/span\\u003e). Similarly, it is thought that the negative selection of \\u003cem\\u003eS. seyhanensis\\u003c/em\\u003e and the natural selection of \\u003cem\\u003eA. boyeri\\u003c/em\\u003e may be due to the abundance of aquatic vegetation in the coastal area of the lake.\\u003c/p\\u003e \\u003cp\\u003eConclusion, this study presented the food items, feeding intensity and feeding habits of northern pike during various seasons and feeding strategy in Sıddıklı Dam Lake, T\\u0026uuml;rkiye. Furthermore, it also revealed the relationships between environmental parameters and feeding intensity. \\u003cem\\u003eEsox lucius\\u003c/em\\u003e showed variations in feeding intensity at seasonal. It was observed that environmental food abundance had no effect on the prey preference of this fish species in the research area. It is thought that the morphological structure of prey fish mostly affects food preference. The present findings on the feeding feature of \\u003cem\\u003eEsox lucius\\u003c/em\\u003e could contribute to the existing knowledge on sustainable management of this potentially prey fishes with economic and ecological value.\\u003c/p\\u003e\"},{\"header\":\"Declarations\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eAcknowledgments\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eWe would like to thank local fisherman Ali Aydemir for helping us catch fish.\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eFunding\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThis work was financially supported by Kırşehir Ahi Evran University, project no. PYO.MYO.4001.15.001.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eData availability\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe datasets are available upon request from the corresponding author.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eEthical approval\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eFish catching and laboratory procedures for this study were approved by the animal experiments local ethics committee (document no:\\u0026nbsp;68429034/05).\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eConsent of publication\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eNot applicable.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eCompeting interests\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe authors declare that no conflicting interests exist\\u003c/p\\u003e\\n\"},{\"header\":\"References\",\"content\":\"\\u003col\\u003e\\n\\u003cli\\u003eAkın Ş. Turgut E (2003) A review paper on the effects of aquatic vegetation on predator-prey interactions. Journal of Agricultural Faculty of Gaziosmanpaşa University 20(2): 49-53.\\u003c/li\\u003e\\n\\u003cli\\u003eAkkan T, Yazicioglu O, Yazici R, Yilmaz M (2018) Assessment of irrigation water quality of Turkey using multivariate statistical techniques and water quality index: Sıddıklı Dam Lake. Desalination and Water Treatment. https://dx.doi.org/10.5004/dwt.2018.22302\\u003c/li\\u003e\\n\\u003cli\\u003eAlp A, Yeğen V, Yağcı-Apaydın M, Uysal R, Bi\\u0026ccedil;en E, Yağcı A (2008). Diet Composition and Prey Selection of Pike, \\u003cem\\u003eEsox lucius, \\u003c/em\\u003ein \\u0026Ccedil;ivril Lake, Turkey. 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Canadian Journal of Fisheries and Aquatic Sciences 53: 161-174.\\u003c/li\\u003e\\n\\u003cli\\u003eCathcart CN, Dunker KJ, Quinn TP, Sepulveda AJ, von Hippel FA, Wizik A, Young DB, Westley PA (2019) Trophic plasticity and the invasion of a renowned piscivore: a diet synthesis of northern pike (\\u003cem\\u003eEsox lucius\\u003c/em\\u003e) from the native and introduced ranges in Alaska, USA. Biological invasions 21: 1379-1392.\\u003c/li\\u003e\\n\\u003cli\\u003eChapman LJ, Mackay WC, Wilkinson CW (1989) Feeding Flexibility in Northern Pike (\\u003cem\\u003eEsox lucius\\u003c/em\\u003e): Fish Versus Invertebrate Prey. Can. J. Fish. Aquat. Sci.\\u003cem\\u003e \\u003c/em\\u003e46: 666-669.\\u003c/li\\u003e\\n\\u003cli\\u003eCraig, JF (1996) Population Dynamics, Predation and Role in The Community. In Craig, JF (ed) Pike: biology and exploitation, London, Chapman and Hall, pp 201-208\\u003c/li\\u003e\\n\\u003cli\\u003eCraig JF (2008) A Short Review of Pike Ecology. Hydrobiologia. http://dx.doi.org/10.1007/s10750-007-9262-3\\u003c/li\\u003e\\n\\u003cli\\u003eDe Santis V, Volta P (2021) Spoiled for Choice during Cold Season? Habitat Use and Potential Impacts of the Invasive \\u003cem\\u003eSilurus glanis\\u003c/em\\u003e L. in a Deep, Large, and Oligotrophic Lake (Lake Maggiore, North Italy). Water. https://doi.org/10.3390/w13182549 \\u003c/li\\u003e\\n\\u003cli\\u003eDidenko AV, Gurbyk AB (2016) Spring diet and trophic relationships between piscivorous fishes in Kaniv Reservoir (Ukraine). Folia Zoologica\\u003cem\\u003e \\u003c/em\\u003e65(1): 15-26.\\u003c/li\\u003e\\n\\u003cli\\u003eEkl\\u0026ouml;v P, Hamrin SF (1989) Predatory Efficiency and Prey Selection: Interactions Between Pike \\u003cem\\u003eEsox lucius\\u003c/em\\u003e, Perch \\u003cem\\u003ePerca fluviatilis \\u003c/em\\u003eand Rudd \\u003cem\\u003eScardinius erythrophthalmus\\u003c/em\\u003e. Oikos. http://dx.doi.org/10.2307/3565330\\u003c/li\\u003e\\n\\u003cli\\u003eElvira B, Nicola GG, Almodovar A (1996) Pike and Red Swamp Crayfish: A New Case on Predator-Prey Relationship Between Aliens in Central Spain. Journal of Fish Biology. http://dx.doi.org/10.1111/j.1095-8649.1996.tb01438.x\\u003c/li\\u003e\\n\\u003cli\\u003eGiarrizzo T, Saint-Paul U (2008) Ontogenetic and seasonal shifts in the diet of the pemecou sea catfish Sciades herzbergii (Siluriformes: Ariidae), from a macrotidal mangrove creek in the Curu\\u0026ccedil;\\u0026aacute; estuary, Northern Brazil. Revista de Biolog\\u0026iacute;a Tropical 56(2): 861-873.\\u003c/li\\u003e\\n\\u003cli\\u003eGotceitas V (1990) Variation in plant stem density and its effects on foraging success of juvenile bluegill sunfish. Environ Biol Fish 27(1): 63-70.\\u003c/li\\u003e\\n\\u003cli\\u003eHacunda JS (1981) Trophic Relationships Among Demersal Fishes in A Coastal Area of the Gulf of Marine. Fishery Bulletin 79(4): 775-788. \\u003c/li\\u003e\\n\\u003cli\\u003eHaught S, Von Hippel FA (2011) Invasive pike establishment in Cook Inlet Basin lakes, Alaska: diet, native fish abundance and lake environment. Biological Invasions 13: 2103-2114.\\u003c/li\\u003e\\n\\u003cli\\u003eHorn HS (1966) Measurement of overlap in comparative ecological studies. The American Naturalist 100: 419-424\\u003c/li\\u003e\\n\\u003cli\\u003eHyslop EJ (1980) Stomach Contents Analysis-A Review of Methods and Their Application. Journal of Fish Biology. http://dx.doi.org/10.1111/j.1095-8649.1980.tb02775.x\\u003c/li\\u003e\\n\\u003cli\\u003eJacobson P, Bergstr\\u0026ouml;m U, Ekl\\u0026ouml;f J (2019) Size-dependent diet composition and feeding of Eurasian perch (\\u003cem\\u003ePerca fluviatilis\\u003c/em\\u003e) and northern pike (\\u003cem\\u003eEsox lucius\\u003c/em\\u003e) in the Baltic Sea. Boreal Environment Research 24(1-6): 1.\\u003c/li\\u003e\\n\\u003cli\\u003eJuanes F, Buckel JA, Scharf FS (2002) Feeding ecology of piscivorous fishes. In: Hart PJB, Reynolds JD (eds) Handbook of fish biology and fisheries, Blackwell Publishing Company, Oxford, pp 267-279\\u003c/li\\u003e\\n\\u003cli\\u003eKangur A, Kangur P (1998) Diet Composition and Size-Related Changes in The Feeding of Pikeperch, \\u003cem\\u003eStizostedion lucioperca \\u003c/em\\u003e(Percidae) and Pike, \\u003cem\\u003eEsox lucius \\u003c/em\\u003e(Esocidae) in The Lake Peipsi (Estonia). Italian Journal of Zoology. http://dx.doi.org/10.1080/11250009809386828\\u003c/li\\u003e\\n\\u003cli\\u003eKek\\u0026auml;l\\u0026auml;inen J, Niva T, Huuskonen H (2008) Pike predation on hatchery-reared Atlantic salmon smolts in a northern Baltic River. Ecology of Freshwater Fish 17: 100-109. \\u003c/li\\u003e\\n\\u003cli\\u003eLangton RW (1982) Diet overlap between the Atlantic cod \\u003cem\\u003eGadus morhua\\u003c/em\\u003e, silver hake, \\u003cem\\u003eMerluccius biliniaris\\u003c/em\\u003e and fifteen other northwest Atlantic fin fish. Fish Bull 80:745-759.\\u003c/li\\u003e\\n\\u003cli\\u003eLiao H, Pierce J, Larscheid G (2002) Diet Dynamics of The Adult Piscivorous Fish Community in Spirit Lake, Iowa, USA 1995-1997. Ecology of Freshwater Fish. http://dx.doi.org/10.1034/j.1600-0633.2002.00015.x\\u003c/li\\u003e\\n\\u003cli\\u003eMagnhagen C, Heibo E (2001) Gape Size Allometry in Pike Reflects Variation Between Lakes in Prey Availability and Relative Body Depth. Functional Ecology 15(6): 754-762. \\u003c/li\\u003e\\n\\u003cli\\u003eMalik DS, Sharma AK, Tyagi D (2019) Food and feeding habits of \\u003cem\\u003eTor tor\\u003c/em\\u003e (Hamilton, 1822) and \\u003cem\\u003eSchizothorox richardsonii\\u003c/em\\u003e (Gray, 1832) inhibiting Bhagirathi River, Tehri Garhwal, India. International Journal of Science and Nature 10(2): 97-103\\u003c/li\\u003e\\n\\u003cli\\u003eMartinho F, S\\u0026aacute; C, Falc\\u0026atilde;o J, Cabral HN, Pardal M\\u0026Acirc; (2012) Comparative feeding ecology of two elasmobranch species, \\u003cem\\u003eSqualus blainville\\u003c/em\\u003e and \\u003cem\\u003eScyliorhinus canicula\\u003c/em\\u003e, off the coast of Portugal. Fish. Bull 110:71-84.\\u003c/li\\u003e\\n\\u003cli\\u003eM\\u0026ecirc;rő TO (2015) The first recording of the threatened species, the European weather loach, \\u003cem\\u003eMisgurnus fossilis\\u003c/em\\u003e (Berg, 1949), in the diet of the pike. Turkish Journal of Zoology 39(5): 967-970.\\u003c/li\\u003e\\n\\u003cli\\u003eNilsson PA, Br\\u0026ouml;nmark C (1999) Foraging among cannibals and kleptoparasites: effects of prey size on pike behavior. Behavioral Ecology 10(5): 557-566.\\u003c/li\\u003e\\n\\u003cli\\u003eNilsson PA, Ran\\u0026aring;ker L, Hulth\\u0026eacute;n K, Nilsson-\\u0026Ouml;rtman V, Br\\u0026ouml;nmark C, Brodersen J (2023) First-season growth and food of YOY pike (\\u003cem\\u003eEsox lucius\\u003c/em\\u003e) are habitat specific within a lake. Fisheries Research. https://doi.org/10.1016/j.fishres.2022.106563\\u003c/li\\u003e\\n\\u003cli\\u003eOkgerman HC, Yardimci CH, Dorak Z, Yilmaz N (2013) Feeding ecology of vimba (\\u003cem\\u003eVimba vimba\\u003c/em\\u003e L., 1758) in terms of size groups and seasons in Lake Sapanca, northwestern Anatolia. Turkish Journal of Zoology 37(3): 288-297.\\u003c/li\\u003e\\n\\u003cli\\u003ePavlović M, Simonović P, Stojković M, Simić V (2015) Analysis of diet of piscivorous fishes in Bovan, Gruža and \\u0026Scaron;umarice reservoir, Serbia. Iranian Journal of Fisheries Sciences 14(4): 908-923\\u003c/li\\u003e\\n\\u003cli\\u003ePearre SJR (1982) Estimating Prey Preference by Predators: Uses of Various Indices, and A Proposal of Another Based on \\u003cem\\u003ex\\u003c/em\\u003e2. Canadian Journal of Fisheries and Aquatic Sciences. http://dx.doi.org/10.1139/f82-122\\u003c/li\\u003e\\n\\u003cli\\u003ePinkas L, Oliphant MS, Iverson ILK (1971) Food Habits of Albacore, Bluefin Tuna, and Bonito in California Waters. Fish Bulletin 152: 1-105. \\u003c/li\\u003e\\n\\u003cli\\u003eSaikia SK (2015) Food and feeding of fishes. What do we need to know?. Transylvanian Review of Systematical and Ecological Research 17(1): 71-84.\\u003c/li\\u003e\\n\\u003cli\\u003eSandlund OT, Museth J, \\u0026Oslash;istad S (2016) Migration, growth patterns, and diet of pike (Esox lucius) in a river reservoir and its inflowing river. Fisheries Research 173: 53-60.\\u003c/li\\u003e\\n\\u003cli\\u003eSoupir CA, Brown ML, Kallemeyn LW (2000) Trophic ecology of largemouth bass and northern pike in allopatric and sympatric assemblages in northern boreal lakes. Canadian Journal of Zoology 78(10): 1759-1766.\\u003c/li\\u003e\\n\\u003cli\\u003eTrella M, Woƚos A (2021) Size and selected characteristics of northern pike (\\u003cem\\u003eEsox lucius\\u003c/em\\u003e L.) commercial and angling catches in Polish inland waters over the long term. Fisheries Aquatic \\u0026amp; Life 29: 108-123\\u003c/li\\u003e\\n\\u003cli\\u003eTyus HM, Beard JM (1990) \\u003cem\\u003eEsox lucius \\u003c/em\\u003e(Esocidae) and \\u003cem\\u003eStizostedion vitreum \\u003c/em\\u003e(Percidae) in The Green River Basin, Colorado and Utah. Great Basin Naturalist 50(1): 33-39\\u003c/li\\u003e\\n\\u003cli\\u003eWinfield IJ, Fletcher JM, Ben James J, (2012) Long‐term changes in the diet of pike (\\u003cem\\u003eEsox lucius\\u003c/em\\u003e), the top aquatic predator in a changing Windermere. Freshwater Biology 57(2): 373-383.\\u003c/li\\u003e\\n\\u003cli\\u003eYazıcı R (2018) Biological Properties of Wels Catfish (\\u003cem\\u003eSilurus glanis\\u003c/em\\u003e L., 1758) in Sıddıklı K\\u0026uuml;\\u0026ccedil;\\u0026uuml;kboğaz Dam. Dissertation, Kırşehir Ahi Evran University\\u003c/li\\u003e\\n\\u003cli\\u003eYazici R, Yazicioğlu O, Yilmaz S, Polat N (2022) Food composition and feeding strategies of an invasive species, \\u003cem\\u003eCarassius gibelio\\u003c/em\\u003e (Bloch, 1782) inhabiting a eutrophic lake in Middle Black Sea region. Indian Journal of Fisheries 69(2): 48-55.\\u003c/li\\u003e\\n\\u003cli\\u003eYazıcıoğlu O, Yılmaz S, Yazıcı R, Erbaşaran M, Polat N (2016) Feeding ecology and prey selection of European perch, \\u003cem\\u003ePerca fluviatilis\\u003c/em\\u003e inhabiting a eutrophic lake in northern Turkey. Journal of Freshwater Ecology 31(4): 641-651.\\u003c/li\\u003e\\n\\u003cli\\u003eYazicioglu O, Polat N, Yilmaz S (2018) Feeding biology of pike, \\u003cem\\u003eEsox lucius\\u003c/em\\u003e L., 1758 inhabiting Lake Ladik, Turkey. Turkish Journal of Fisheries and Aquatic Sciences 18(10): 1215-1226.\\u003c/li\\u003e\\n\\u003cli\\u003eYilmaz M, Gaffaroglu M, Polat N, Emiroglu O, (2010) The Dietary Regime of The Pike (\\u003cem\\u003eEsox lucius\\u003c/em\\u003e L., 1758) in Lake Uluabat (Bursa, Turkey), Journal of Animal and Veterinary Advances 9 (3): 651-653.\\u003c/li\\u003e\\n\\u003cli\\u003eYılmaz M, Polat N (2005) Digestive System Content of the Pike (\\u003cem\\u003eEsox lucius\\u003c/em\\u003e L., 1758) Living in Simenit Lake (Terme-Samsun). Fırat University Journal of Engineering Science 17(3): 589-598. \\u003c/li\\u003e\\n\\u003cli\\u003eYılmaz M, \\u0026Uuml;nver E (2014) Feeding Dietary of Pike Esox lucius L.,1758 Inhabiting Sıdıklı K\\u0026uuml;\\u0026ccedil;\\u0026uuml;kboğaz Dam Lake. The Black Sea Journal of Sciences 4(10): 37-45\\u003c/li\\u003e\\n\\u003c/ol\\u003e\"}],\"fulltextSource\":\"\",\"fullText\":\"\",\"funders\":[],\"hasAdminPriorityOnWorkflow\":false,\"hasManuscriptDocX\":true,\"hasOptedInToPreprint\":true,\"hasPassedJournalQc\":\"\",\"hasAnyPriority\":false,\"hideJournal\":true,\"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\":\"researchsquare\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":true,\"externalIdentity\":\"\",\"sideBox\":\"\",\"snPcode\":\"\",\"submissionUrl\":\"/submission\",\"title\":\"Research Square\",\"twitterHandle\":\"researchsquare\",\"acdcEnabled\":true,\"dfaEnabled\":false,\"editorialSystem\":\"\",\"reportingPortfolio\":\"\",\"inReviewEnabled\":false,\"inReviewRevisionsEnabled\":true},\"keywords\":\"Diet, feeding strategy, feeding habits, food items, predator fish, Esox lucius\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-4656714/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-4656714/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"\\u003cp\\u003eFish samples were collected monthly from Dam Lake from September 2015 to August 2016 and a total of 133 northern pike, \\u003cem\\u003eEsox lucius\\u003c/em\\u003e individuals were examined for this study. The feeding intensity showed the highest value during summer (FI\\u0026thinsp;=\\u0026thinsp;1.59) while the lowest value was during winter (FI\\u0026thinsp;=\\u0026thinsp;0.51). Temperature was identified as the most critical environmental variable influencing feeding intensity. The high similarity in the diet of northern pike was observed between seasons. Stomach content analysis indicated that this species consumed only prey fishes. The most eaten of prey fishes were the \\u003cem\\u003eTinca tinca\\u003c/em\\u003e contributing 44.83% by number and 56.16% by frequency of occurrence. There was little variation in feeding features between seasons. The northern pike more specialized on \\u003cem\\u003eT.tinca\\u003c/em\\u003e and \\u003cem\\u003eAtherina. boyeri\\u003c/em\\u003e. According to the findings of the study, \\u003cem\\u003eEsox lucius\\u003c/em\\u003e was a primary predator and showed a specialist feeding behavior, feeding only on fish (mainly T. \\u003cem\\u003etinca\\u003c/em\\u003e and \\u003cem\\u003eA. boyeri\\u003c/em\\u003e). Environmental prey abundance did not affect the prey selection of this fish species in Sıddıklı Dam Lake.\\u003c/p\\u003e\",\"manuscriptTitle\":\"Diet and Feeding Strategy of Northern Pike, Esox lucius L., 1758 Inhabiting A Deep Dam Lake from Located Central Anatolia, TÜRKİYE\",\"msid\":\"\",\"msnumber\":\"\",\"nonDraftVersions\":[{\"code\":1,\"date\":\"2024-08-09 20:53:41\",\"doi\":\"10.21203/rs.3.rs-4656714/v1\",\"editorialEvents\":[{\"type\":\"communityComments\",\"content\":0}],\"status\":\"published\",\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"researchsquare\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":true,\"externalIdentity\":\"\",\"sideBox\":\"\",\"snPcode\":\"\",\"submissionUrl\":\"/submission\",\"title\":\"Research Square\",\"twitterHandle\":\"researchsquare\",\"acdcEnabled\":true,\"dfaEnabled\":false,\"editorialSystem\":\"\",\"reportingPortfolio\":\"\",\"inReviewEnabled\":false,\"inReviewRevisionsEnabled\":true}}],\"origin\":\"\",\"ownerIdentity\":\"0c5ac962-ef1c-49bf-9519-3adb6f327b47\",\"owner\":[],\"postedDate\":\"August 9th, 2024\",\"published\":true,\"recentEditorialEvents\":[],\"rejectedJournal\":[],\"revision\":\"\",\"amendment\":\"\",\"status\":\"posted\",\"subjectAreas\":[],\"tags\":[],\"updatedAt\":\"2024-08-09T20:53:44+00:00\",\"versionOfRecord\":[],\"versionCreatedAt\":\"2024-08-09 20:53:41\",\"video\":\"\",\"vorDoi\":\"\",\"vorDoiUrl\":\"\",\"workflowStages\":[]},\"version\":\"v1\",\"identity\":\"rs-4656714\",\"journalConfig\":\"researchsquare\"},\"__N_SSP\":true},\"page\":\"/article/[identity]/[[...version]]\",\"query\":{\"redirect\":\"/article/rs-4656714\",\"identity\":\"rs-4656714\",\"version\":[\"v1\"]},\"buildId\":\"qtupq5eGEP_6zYnWcrvyt\",\"isFallback\":false,\"isExperimentalCompile\":false,\"dynamicIds\":[84888],\"gssp\":true,\"scriptLoader\":[]}","source_license":"CC-BY-4.0","license_restricted":false}