Numerous uncertainties in the multifaceted global trade in frogs’ legs with the EU as the major consumer

19 The commercial trade in frogs and their body parts is global, dynamic, and occurs in extremely 20 large volumes (in the thousands of tonnes/yr or billions of frogs/yr). The E uropean Union 21 remains the single largest import er of frogs’ legs, with most frogs still caught from the wild . 22 Among the many drivers of species extinction or population decline (e.g., due to habitat loss, 23 climate change, disease , etc.), overexploitation is becoming increasingly more prominent. 24 Because of global declines and extinctions, new attention is being focused on these markets, in 25 part to try to ensure sustainability. While the trade is plagued by daunting realities of data 26 deficiency and uncertainty, and the conflicts of commercial interests associated with these data, 27 one of the only things that is clear is that EU countries are most responsible for the largest 28 portion the international trade in frogs’ legs of wild species. Over decades of exploitation, the 29 EU imports have contributed to a decline in wild frog populations in an increasing number of 30 supplying countries, such as India and Bangladesh, as well as Indonesia, Turkey, and Albania 31 more recently . However, there have been no concerted attempts by the EU and the export 32 countries to ensure sustainability of th is trade. Further work is needed to validate species 33 identities, secure data on wild frog populations, establish reasonable monitored harvest/export 34 quotas and disease surveillance, and ensure data integrity, quality, and security standards for 35 frog farms . Herein, we call upon those countries and their representative governments, to 36 assume responsibility for the sustainability of the trade. The EU should take immediate action 37 to channel all imports through a single centralized database and list sensitive species in the 38 Annexes of the EU Wildlife Trade Regulation. Further listing in CITES (the Convention on 39 International Trade in Endangered Species of Wild Fauna and Flora) can enforce international 40 trade restrictions. More joint-efforts are needed to improve regional monitoring schemes before 41 the commercial trade causes irreversible extinctions of populations and species of frogs. 42 43

44 Amphibians, biodiversity, CITES, disease, over-exploitation, sustainability, taxonomic status, 45 wildlife trade 46 47 48 49 50 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243

51 52 53 Three decades ago, i nitial signs of global declines in amphibian populations were reported 54 (Blaustein and Wake 1990, Pechmann and Wilbur 1994). Thirteen years ago, Stuart et al. (2008) 55 edited their compendium “Threatened World of Amphibians” as a result of the Global 56 Amphibian Assessment and synthesized knowledge on the science and threats detrimentally 57 impacting amphibian species on a global scale. Threats such as habitat destruction (Cox et al. 58 2006), pollution (Blaustein and Johnson 2003), domestic use and trade (Mohneke 2011; Turvey 59 et al. 2021), international trade (Andreone et al. 2006; Carpenter et al. 2014; Auliya et al. 2016), 60 and climate change (Blaustein et al. 2010) have been well studied in many areas, but amphibians 61 are also particularly vulnerable to pathogens, such as ranavirus es (Cunningham et al. 1996; 62 Daszak et al. 1999; Miller et al. 2011; Bayley et al. 2013), mycotic diseases (Daszak et al. 1999; 63 Fitzpatrick et al. 2018), and parasites (Kim et al. 2016). A recent study also revealed that frogs 64 act as intermediate hosts of the parasite Alaria alata, and human consumption of frogs’ legs 65 containing larvae of the parasite can promote alariosis, a potentially deadly parasitic infection 66 (Korpysa-Dzirba et al. 2021) . However, it has also been emphasized that these threats can 67 causally and synergistically interact (Ficetola et al. 2007; Sodhi et al. 2008; Hayes et al. 2010; 68 Ford et al. 2020). As early as 1993, amphibian mortalities were attributed to the chytrid fungus, 69 Batrachochytrium dendrobatidis, Bd (Berger et al. 1998), with several possible extinctions and 70 its spread across central America up to the late 1980s (Cheng et al. 2011) . In the years that 71 followed, the scale of this panzootic disease (chytridiomycosis), became apparent and scientific 72 papers highlighted the fungal disease with more than 500 amphibian species around the world 73 affected by Bd (Scheele et al. 2019). In addition, a new fungus specifically affecting 74 salamanders, Batrachochytrium salamandrivorans (Bsal), was also identified (Martel et al. 75 2013). Notably, during a human pandemic , commercial trade is both the principal source and 76 the most viable means of spreading emerging zoonotic diseases (see Vora et al. 2022). 77 78 The i nternational trade of live amphibians infected with either Bd or Bsal has since been 79 highlighted (e.g., Fisher and Garner 2007; Kriger and Hero 2009, Catenazzi et al. 2010; Yuan 80 et al. 2018; Fitzpatrick et al. 2018; Hughes et al. 2021; Thumsová et al. 2021), and its 81 detrimental impact threatens naïve populations with extinction (Martel et al. 2014; Stegen et al. 82 2017). To date, considerable research has contributed to an increased understanding of regional, 83 national, and global declines of amphibians and understanding of the spread and pathogenicity 84 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 of diseases. However, the impact of wildlife trade and associated diseases on local populations 85 remains poorly understood. 86 87 While the international amphibian pet trade includes a broader range of species with many frogs 88 still coming from the wild (Auliya et al. 2016; Hughes et al . 2021), species harvested for 89 consumption as food (e.g., frogs’ legs trade), represent only a small number of species . 90 However, annual exports for the food trade are in the thousands of ton nes, or hundreds of 91 millions of individuals (Kusrini and Alford 2006; Gratwicke et al. 2010). Notwithstanding the 92 considerable implications on species survivorship, we know less about the impacts of trade than 93 most other threats in terms of effect on local biotic communities and their ecosystems, the 94 spread of diseases, and issues resulting from the interaction of wild-caught and farmed species 95 (Lutz and Avery 1999; Dökenel and Özer 2019; Ribeiro et al. 2019). While the history of frog 96 farming is marked by many setbacks, it has steadily increased scale in recent years (FAO 2020; 97 Dodd and Jennings 2021). Despite this growth , potential ecological impact of frog farms is 98 often neglected (see below) and over-exploitation of wild-caught frogs is ongoing (Çiçek et al. 99 2020; Hughes et al. 2021 ; IUCN SSC Amphibian Specialist Group 2020h). In addition, the 100 taxonomic status of taxa exploited for consumption is not unequivocally clarified [e.g., the 101 Fejervarya cancrivora complex at least three species (Kotaki et al. 2010; Kurniawan et al. 2011; 102 Yodthong et al. 2019), t axonomic challenges in Pelophylax spp., i.e. , P. lessonae and P. 103 ridibundus (Holsbeek et al. 2008; Holsbeek and Jooris 2010; Hauswaldt et al. 2012), and the 104 Limnonectes kuhlii complex (e.g., McLeod et al. 2011; Dehling and Dehling 2017; Stuart et al. 105 2020; Suwannapoom et al. 2021)]. Likewise, it is necessary to create an accurate and up-to-date 106 database of the role the ma jor consuming countries take in terms of numbers of wild 107 caught/farmed animals, supplying countries, harvest locations, farms involved (cf. with data 108 records of the Law Enforcement Management Information System, LEMIS), mortality figures, 109 etc., with a focus on the European Union (EU) (Veith et al. 2000; Potočnik 2012; Çiçek et al. 110 2021) and Switzerland (see Dubey et al. 2014; Dufresnes et al. 2018). For example, TRACES 111 is an online platform of the EU established to certify imports of animals and their products 112 according to sanitary standards (https://ec.europa.eu/food/animals/traces_en, see Suppl. Inf. 3) 113 but lacks species-specific data, missing an important opportunity to monitor species in trade. 114 115 Enforcement of laws, regulations, and quotas or harvest limits is particularly challeng ing for 116 transport and trade of frogs' legs . Many species are very similar in their morphology and as 117 products are skinned, processed , and frozen , gross mislabelling is likely and hard to verify 118 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 (Veith et al. 2000; Dittrich et al. 2017; Ohler and Nicolas 2017). In fact, it is impossible for 119 enforcement authorities to assign frogs' l egs to a species without genetic methods , hence 120 authorities can only check documents enclosed in a consignment and assume that they are true. 121 122 Herein, we provide an overview on the EU’s central role as primary ultimate destination for the 123 global trade in frogs’ legs and its corresponding responsibility for resulting ecological risks and 124 impacts. Furthermore, our review summarizes knowledge on the current status of international 125 trade in both live frogs and parts for human consumption. We primarily outline certainties (e.g., 126 loss of biodiversity, destabilization of ecological communities in their ecosystems, flawed 127 farming operations, genetic pollution) against the manifold uncertainties underlying this trade 128 (lack of documentation to asses s sustainability of trade ; species identification of individual 129 frozen frogs, skinned frog bodies, or parts thereof; and international regulation of species not 130 listed in the appendices of CITES ). Clear i dentification of these deficiencies should oblige 131 policy makers from responsible consuming countries to follow revised and newly implemented 132 legislation and, where appropriate, apply the precautionary principle as a crucial safeguard for 133 the survival of many amphibian species. Understanding the dimensions of the frogs’ legs trade 134 is challenging (since much of the global data is not available after 2009 ), even when we had 135 better data (Figure S1). Initially, Asia dominated export trade (especially India, Indonesia, and 136 China, but China dropped out in 2007), followed by Europe (until 2006) and the US (a small 137 proportion, almost entirely gone by 2008) (Atlas of Economic Complexity 2022; see Suppl. Inf. 138 1, Fig. 1). But these trends have not remained consistent and many complexities have revealed 139 themselves more recently. Thus, understanding and updating our knowledge of global trade is 140 paramount to effective interventions if we want to ensure a sustainable trade . We offer these 141 suggestions to enable long-term sustainability of the trade, as well as the amphibian populations 142 it is dependent upon and the humans whose livelihoods are intricately intertwined. 143 144 145

146 147 Apart from information retrieved from previous studies (Altherr et al. 2011; Auliya et al. 2016), 148 this review is mainly based on a systematic literature survey from conscientiously extracted 149 relevant published information related to the international trade in frogs’ legs (e.g., taxonomy, 150 ecology, disease, threats, and conservation). For the identification of relevant publications, we 151 used a number of English [e.g., x-country, x-species (e.g., Fejervarya) frog, trade, frogleg / 152 frogs’ legs , frog meat, commercial, culture, farming, threats (that could specifically be 153 “pollution” or “climate change ”), and Indonesian [katak/kodok (for “frog”), Jawa, x-jenis 154 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 (scientific name of a given species), dagang (trade), ancaman (threat), kaki (leg), pada (thigh)] 155 search terms in Google Scholar searches . These terms were used because they would be in 156 publications that feature amphibian trade in either English or Bahasa Indonesia. Number and 157 order of terms entered per language was changed during searches. Searches in Bahasa Indonesia 158 were implemented because Indonesia is recognized as the current major supplier of frogs’ legs 159 to European markets (e.g., Warkentin et al. 2009; Altherr et al. 2011; Potočnik 2012 ; 160 EUROSTAT 2020). Also, publications from the International System for Agricultural Science 161 and Technology (AGRIS) of the FAO were scanned for “frog legs” (https://agris.fao.org/, see 162 Suppl. Inf. 3). 163 164 Taxonomy largely followed F rost (2021) and relevant papers that outline cryptic, look -a-like 165 species, or where taxonomic status remain s uncertain (e.g., Holsbeek et al. 2008; Hasan et al. 166 2012; Yodthong et al. 2019). With reference to the North American bullfrog, Rana catesbeiana 167 listed in the genus Lithobates (Dubois 2006) , most recent studies now list the genus as 168 Aquarana (Dubois et al. 2021) while the trade data still refer to Lithobates. In order to avoid 169 confusion, in this study we use Lithobates. In addition, AmphibiaWeb 170 (https://amphibiaweb.org/, see Suppl. Inf. 3) was surveyed to filter information relevant to 171 species involved in the co mmercial food and pet trade. Databases documenting species and 172 volumes imported into the EU include EUROSTAT 173 (https://ec.europa.eu/eurostat/web/main/data/database, see Suppl. Inf. 3), and were filtered 174 from the sub-database “EU trade since 1988 by HS2,4,6 and CN8” (categories 02082000 and 175 02089070 are frogs’ legs fresh, c hilled, or frozen) selected for the time 2010 to 2019 . 176 Remarkably, imports of live frogs are not specifically documented by EUROSTAT , but 177 assigned to a n unspecific customs tariff number, generally describ ing "animals, other, live". 178 Also, there is distinction between import of “wild” versus “cultured/farmed” specimens. We 179 also extracted import data from the United States Fish and Wildlife Service (USFWS) and 180 LEMIS databases for the period 2015-2020, focusing on species that are traded either in kg or 181 in large numbers and known to be relevant for human consumption (e.g., Hoplobatrachus 182 rugulosus and Lithobates catesbeianus). 183 184 A study was simultaneously conducted for a current snapshot/analysis of the French market 185 (the EU’s major consuming nation of frogs’ legs). Data were retrieved from the French Customs 186 statistics for the period 2010-21 (LeKiosque.finances.gouv.fr; accessed 16 April 2019 and 26 187 April 2022) . Additionally, in December 2021, an online survey of the French market was 188 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 carried out. Websites used for this included major supermarkets, frozen food brands, Asian food 189 supermarkets (i.e., Auchan, Cora, Monoprix, Picard, Tang Frères, etc.). Another market survey 190 of e-mail alerts was conducted between 23 rd November 2021 – 9th February 2022. The survey 191 was conducted using Google Alert with the keywords "frog legs" in French, and in singular and 192 plural forms, asking to receive all new content regardless of the source (News, Blogs, Web). 193 The commercial offers were sorted and analysed. 194 195 An advanced search on “The IUCN Red List” based on the following filters; (a) Taxonomy > 196 Amphibia, (b) Threats > Biological Resource use > Intentional use, and (c) Use and Trade > 197 Food (Human) was also completed . The resulting species were assigned to their native 198 regions/countries and tabulated with information on current IUCN Red List status (IUCN 199 2021), CITES appendix listing, and information indicating a regional overharvest or 200 overexploitation in general (see Table 3, Suppl. Inf. 2, 4). Subsequently, all CITES -listed 201 amphibian species were filtered in SPECIES+ (https://www.speciesplus.net, see Suppl. Inf. 3), 202 a website developed by CITES and UNEP -WCMC that includes all species in 203 appendices/annexes of CITES (n.b., only 2.5% of amphibian species are CITES listed), the EU 204 Wildlife Trade Regulations, and the Conservation of Migratory Species (CMS). 205 CITES Appendix listings were checked with the species filtered in the IUCN Red List where 206 international trade for consumption (food) was indicated. Those species were entered in the 207 CITES trade database (https://trade.cites.org/, see Suppl. Inf. 3) to record information on trade 208 (e.g., years, volumes, countries of export and import, and sources of trade ), and to check if 209 specific population trends are emerging. Indonesian harvest and export quotas were surveyed 210 in the period 2015 to 2021, according to the annu al published quota lists ( e.g., Indonesian 211 Ministry of Environment and Forestry 2021). 212 213 Once we had a list of species potentially traded for food, we were able to pair that list with the 214 IUCN data mapping species distributions. First , we downloaded amphibi an ranges from the 215 IUCN website (https://www.iucnredlist.org/). We then uploaded these into ArcMap 10.8 and 216 selected all species in trade using the “joins and relates” function, before extracting these 217 species. Species ranges were then dissolved so that each species was represented by a single 218 polygon (though this could be a multipart polygon). This was then split into groups of 30 species 219 before overlaps were counted using the “count overlapping polygons” toolbox for each subset, 220 this was purely for processing and all species were included in total . These were then all 221 converted to a raster with a 10km resolution, and each stack was summed using the “mosaic to 222 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 new raster” function to sum values and map the number of species being consumed in each 223 geographic area. 224 In addition, we used “union” to combine species’ ranges with a map of the world (from thematic 225 mapper), the species range country combinations dissolved to list each species once for each 226 country it was in, and the summary statistics tool was used to calculate the number of species 227 being traded for consumption for each country. This table was then related to the original 228 country map to show the number of species being traded for consumption per country. This was 229 then repeated for just those species being traded internationally for consumption. 230 231 232

233 234 After describing current import volumes of frogs' legs into the EU and the main supply regions, 235 we highlight the species that make up the international frogs' leg trade, describe national 236 consumption trends, and finally provide information on threats impacting species/populations, 237 indicate amphibian population trends, and broader ecological impacts of the frogs’ legs trade. 238 239 240 The role of the European Union and its member States 241 242 243 In the study period 2010 to 2019, total imports of frog’s legs into the EU numbered 40,698,800 244 kg. This total weight can be converted , when 1 kg equals 20-50 individual frogs (Veith et al. 245 2000), to at least 814 million and up to roughly 2 billion frogs. According to Indonesia’s annual 246 harvest/export quotas for F. cancrivora , for the period 2016-2020, 1 kg equated to 15-22 247 individual specimens (Indonesian Ministry of Environment and Forestry 2016-2020). 248 Indonesia’s annual quotas appear to be set arbitrarily, there is a complete lack of data as a basis 249 for sustainable trade, including information on the number of individuals that die prior to export. 250 As early as 1986, Niekisch reported an estimated pre-export mortality rate of 10 -20%, but 251 mortality during the export process may be highly variable. Herein, we assume that every export 252 also includes an estimated number of dead animals for which the importer is also responsible . 253 Wholesalers of live animals have been found to have mortality rates of around 45% for 254 amphibians, meaning live trade levels may need to be in high er volumes to satisfy demand 255 when many frogs die in transit, with many coming from the wild (Ashley et al. 2014). 256 257 In the study period 2010 -19 (EUROSTAT 2020) Belgium leads EU countries in imported 258 quantities of frogs' legs , with a total of 28,430 tonnes (69.8%), ahead of France with 6,790 259 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 tonnes (16.6%), followed by the Netherlands (2,620 tonnes; 6.4%), Italy (1,790 tonnes; 4.3%), 260 and Spain ( 923.4 tonnes ; 2.2%) (Table 1) . Smaller quantities were imported by the United 261 Kingdom (68,8 tonnes), Croatia (28,5 tonnes), the Czech Republic (27,8 tonnes), Poland (12,5 262 tonnes), Romania (2,8 tonnes), and Germany (1,8 tonnes). Within the EU, Belgium re-exports 263 a large part of its imports to other EU countries . For example, Belgium re -exported 20,920 264 tonnes to France (>73% of all its imports in the study period) and 1,410 tonnes to the 265 Netherlands (ca. 5% of all its imports in the study period), accordingly, Belgium consumed 266 21% of its total imports. 267 268 Table 1. Main EU importers/consumers and suppliers of frogs’ legs (in tonnes) for the period 2010-2019. Source: 269 EUROSTAT (2020) 270 Major EU importers Major suppliers of frogs’ legs into the EU Belgium 28,429 Indonesia 30,019.4 France 6,794.4 Vietnam 8,439.4 Netherlands 2,621.5 Turkey 1,593.7 Italy 1,787.2 Albania 586,5 Spain 923.4 271 272 France and the frogs’ legs trade 273 274 Due to the introduction of advanced technologies of freezing methods in the 1970s, storage 275 constraints were reduced, and transport routes of frogs’ legs became possible. This transformed 276 traditional frogs’ leg trade in France , b ringing some local frog populations to the brink of 277 extinction (Ohler and Nicolas 2017 and references therein). Since at least the 1980s, France has 278 historically been considered the main consumer of frogs' legs. According to Le Serrec (1988), 279 France import ed a total of 4,522 tonnes of frogs ’ legs in 1983. Based on this fact, France 280 initiated studies to gain clarity on species composition as well as potential ecological damage 281 from intense commercialized trade (MNHN 2012; Ohler and Nicolas 2017). 282 283 From 2010-19 France imported 30,015 tonnes of fresh, refrigerated, or frozen frogs' legs (ca. 284 600-1,500 million frogs; Veith et al. 2000), according to French customs statistics 285 (https://leKiosque.finances.gouv.fr/). France's main suppliers are Indon esia (24,102 tonnes or 286 80.3%), Vietnam (3,941 tonnes or 13.1%), Turkey (1,017 tonnes or 3.4%), Belgium (226 tonnes 287 or 0.8%), and Albania (219,6 tonnes, 0.7%). For the same period, the quantities imported from 288 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 Belgium to France differ widely depending on whether the data source is Eurostat or French 289 customs due to two different statistical concepts. France seperately lists the country of direct 290 export origin and country of original export when the country of origin is not an EU country. 291 Original origin prevails in the French statistical data. As a result, some frogs' legs are considered 292 by the French methodology as imported from Indonesia and not from Belgium, even if they 293 have transited through Belgium. Annual imports did not fluctuate significantly between 2017 294 and 2020, with an average of 2,669 tonnes/year. A drop to 1,826 tonnes is prominent in 2021, 295 still a relatively high figure despite the paralysis of international trade due to Covid -19. 296 Similarly, France also is a hub for re-exportation of frogs' legs. From 2017-20, France shipped 297 385 tonnes of frogs’ legs, mainly destined for markets in Belgium (292 tonnes; 75.8% of total 298 tonnage shipped), Luxembourg (24,4 tonnes; 6.4%), and Germany (16,6 tonnes; 4.3%). In 299 2021, it is notable that France also re-exported 13,9 tonnes (3.6%) to Vietnam. 300 301

of the online market survey in December 2021 indicate 20 frogs’ legs food products 302 readily available. Of these 20 products, 11 originated from Indonesia, three from Vietnam, one 303 from France, and one from the "EEC (Turkey, Albania, etc.)". This last indication is confusing 304 because the European Economic Community (EEC) was dissolved in 1993 excluding Turkey 305 and Albania and both are not EU member States . With regard to the indication of France as a 306 source country, these products are pre-cooked frogs' legs that do not originate from France and 307 the species indicated is "wild Limnonectes [Rana] macrodon" endemic to western Indonesia 308 (cf. Table 2). Four sources do not provide information on the country of origin within the 309 product description or packaging. Regarding species name, six sources indicate Rana 310 macrodon, three Fejervarya cancrivora, another three Hoplobatrachus rugulosus, one “Rana 311 macrodon or Fejervarya cancrivora” (here we assume the sourcing from different suppliers, 312 resulting in insufficient traceability for species identification), and one Rana esculenta. 313 For six sources, both product description and packaging do not indicate a species name. With 314 regard to EU legislation, lack of information (species or country of origin) is a violation of EU 315 rules [Commission Regulation (EC) No 2065/2001 of 22 October 2001 detailing rules for the 316 application of Council Regulation (EC) No 104/2000 as regards informing consumers about 317 fishery and aquaculture products ; https://eur-lex.europa.eu/legal-318 content/EN/TXT/HTML/?uri=CELEX:32001R2065&from=FR). In eight sources, origin is 319 highlighted as "wild", three refer to "fishing" (e.g., fresh water, rice fields), and in one indicates 320 "collected" as the source . Not a single product, however, indicates a captive bred or farmed 321 source. Besides raw or cooked frogs’ legs, "frairine" is also offered for sale, a mixture of pork 322 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 and frogs’ legs seasoned with white wine. For this mixed product, there is no information on 323 the origin or species involved. 324 325 An additional market survey through Google Alert for more than 10 weeks (see Methods) 326 identified 38 commercial offers for frogs' legs (20 from Belgium and 18 from France). 327 Regarding the offers from France, trends from the December 2021 study are largely confirmed, 328 with only one offer indicating an origin "Vietnam and/or Indonesia captive bred". 329 330 In addition to imports, the French market is also supplied with wild-caught native species. Short 331 marketing circuits, such as local r estaurants, are supplied with Rana temporaria, a nationally 332 protected species in France 333 (https://www.legifrance.gouv.fr/loda/id/JORFTEXT000017876248/, accessed April 2022, see 334 Suppl. Inf. 3). Despite the legal framework for harvest, numerous exemptions are granted. For 335 example, >2 million R. temporaria are legally caught each year in the Franc he-Comté region 336 (https://www.bourgogne-franche-comte.developpement-durable.gouv.fr/ranaculture-337 bourgogne-franche-comte-dossiers-de-a6583.html, accessed June 2022, see Suppl. Inf. 3). An 338 exemption may exist if an offtake of <1500 frogs is requested, as this is considered "familial". 339 Poaching offences are also recorded and a distinction is made between ca ptures without a 340 permit, those exceeding quotas, or if the capture s are outside authorised time periods. In 341 October 2018, a couple was fined €2500 for the capture of 4000 R. temporaria, even though 342 they possessed a permit for the capture of 1000 specimens ( https://robindesbois.org/en/a-la-343 trace-n23-le-bulletin-de-la-defaunation/RobindesBois, "On the Trail" No. 23, 2019). In the 344 same year, during eight inspections and three searches conducted under a judicial warrant , a 345 total of 171 traps were seized, enabling the release of 17,950 grass frogs (R. temporaria) and 346 10 m3 of eggs into the natural environment (Office national de la chasse et de la faune sauvage; 347 ONCFS, May 9, 2018). 348 349 Major suppliers of species for the frogs’ legs industry in the EU 350 351 There is no doubt that the trade in frogs' legs for consumption is a global issue, with most 352 countries involved in th e trade as exporter, importer, or some combination (Gratwicke et al. 353 2010; Suppl. Inf. 1, Figs. 2,3 ). In recent decades there have been four major source regions 354 exporting edible frogs or body parts (wild and/or farmed) into the EU: (1) East Asia, i.e., China 355 and Taiwan (Warkentin et al. 2009; Altherr et al. 2011; Shreshta 2019), (2) Southeast Asia, i.e., 356 Indonesia and Vietnam (Niekisch 1986; Kusrini and Alford 2006; Warkentin et al. 2009; 357 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 Gratwicke et al. 2010; Ohler and Nicolas 2017; Shreshta 2019), (3) South Asia, i.e. , India and 358 Bangladesh (Niekisch 1986; le Serrec 1988; Warkentin et al. 2009), and (4) eastern Europe i.e., 359 Turkey and Albania (Warkentin et al. 2009; Şereflişan and Alkaya 2016; Çiçek et al. 2021). 360 The United States, another major importing country for frogs and their body parts, is supplied 361 from Asia and South America (Warkentin et al. 2009; US LEMIS Database 2015-2020). Based 362 on LEMIS data, main suppliers for the US market for L. catesbeiana were Mexico (labelled as 363 wc, “wild capture”), Ecuador (farmed), and China (farmed) . Hoplobatrachus rugulosus was 364 imported from Thailand (farmed) and Vietnam (wc), and L. forreri only from Mexico. 365 For most recent trade routes from source countries to importers and consumers into the EU, see 366 Figure 1. 367 368 369 370 Figure 1. The EU as the major consuming region of frog’s legs in the period 2010 -2019, with major supplying 371 countries in SE-Asia (Indonesia, Vietnam) and eastern Europe (Turkey, Albania), and major importing countries 372 (Belgium, France, Netherlands, Italy and Spain). Sources: EUROSTAT 2020 and TRAFFIC (2018) TradeMapper 373 - a tool for visualizing trade data. 374 375 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 Within the study period 2010 -19, Indonesia clearly represents the leading supplier for the 376 European Union’s frogs’ legs with 30,019.4 tonnes (74%), followed by Vietnam ( 8,439.4 377 tonnes; 21%), Turkey (1,593.7 tonnes; 4%), and Albania (586,5 tonnes; 1%) (Table 1, Fig. 1). 378 Comparatively small er amounts were s upplied by China ( 37,7 tonnes ), India ( 15 tonnes ), 379 Thailand (9,2 tonnes), Malaysia ( 7,6 tonnes), and South Korea ( 0,3 tonnes), resulting in less 380 than 1% of the EU’s total imports (EUROSTAT 2020). 381 382 Indonesia. - Europe has been the major importer of frogs’ legs for many decades, with exports 383 from Indonesia contributing to 83% of all European imports (Kusrini and Alford 2006): Already 384 in 1969, Indonesia exported frog’s legs (as fishery products; Mikrimah 2009) to Europe, and in 385 the 1970s, Indonesia was considered the third largest exporting country of frogs’ legs after India 386 and Bangladesh (Susanto 1994 ; Warkentin et al. 2009). While EU imports of frog’s legs 387 exported from Indonesia amounted to > 3 ton nes of frog’s legs in 1987, exports in 1993 388 increased to 4,7 tonnes, corresponding to 94-235 million individual frogs (cf. Veith et al. 2000). 389 Species involved in the international food trade are mainly represented by members of the 390 family Dicroglossidae (Fejervarya and Limnonectes) (Kusrini 2005). H owever, at least 14 391 anuran species are exploited for the food trade, and just four ‘species’ dominate the trade 392 (Fejervarya cancrivora, F. limnocharis, L. macrodon, and Lithobates catesbeianus). Of these, 393 only the latter species, the non-native to Indonesia , L. catesbeianus, is cultured from farms 394 (Altherr et al. 2011) (Table 3). According to Kusrini (2005), the export of 28-142 million frogs 395 annually is approximately only one seventh of the animals harvested for the domestic market 396 across Indonesia, with many smaller species consumed in Indonesia (local species are favoured) 397 and larger ones of at least 100 mm snout-vent length (only about one eighth of the frogs caught) 398 are destined for exports (Kusrini 2005; Kusrini and Alford 2006). While major harvest regions 399 in Indonesia include Sumatra and Java (Kusrini and Alford 2006), exploitation of anurans for 400 food in Kalimantan appears to be less common, but frog’s legs are traded “from Sulawesi to 401 big exporting cities such as Makassar or Jakarta before leaving the country” (Iskandar 2014). 402 Export quotas within Indonesia list species, but on reaching the EU species level information 403 is not recorded (see Table 2). DNA analysis showed that Fejervarya cancrivora was clearly the 404 most dominant species i mported into the EU, and imports declaring other species i.e. , 405 Limnonectes macrodon, F ejervarya limnocharis, and Lithobates catesbeiana, had been 406 mislabelled (Ohler and Nicolas 2017). 407 408 409 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 Annual export quotas . - Annually, Indonesian authorities publish harvest and export quotas 410 of CITES and non -CITES species native to the Indonesia (but possibly not the actual export 411 values). For species listed in Table 2, harvest/export quotas issued for the period 2015 -2021 412 were determined (Indonesian Ministry of Environment and Forestry 2015-2021). 413 Among quotas established for edible frog species, trade for the purpose of “consumption” is 414 indicated for both Fejervarya cancrivora and F. limnocharis. However, only in 2015, for F. 415 limnocharis, a specific number of individuals was designated for consumption (Table 2). While 416 export quotas for F. cancrivora in 2015 were only considered for pets (according to the recorded 417 details), in 2016 a 37,155 -fold increased quota was set for consumption purposes. From then 418 onwards, quota figures declined steadily, stagnating in the last two years with the collapse in 419 2019 remaining unexplained. It also remains unclear what reasons the number of individuals 420 per kilo were reduced as of 2018 (Table 2). In 2015-16, export quotas for skins of Limnonectes 421 macrodon were established, and thereafter no quotas were allocated to the species. There is no 422 information on the whereabouts or use of the skinned bodies and the fact why no quotas have 423 been established for the species since 2017 (Table 2). 424 425 Table 2. Indonesian export quotas of species known to be consumed nationally and internationally; 426 cons=consumption; indiv. = individuals; SVL= snout-vent length. Sources: Indonesian Ministry of Environmen t 427 and Forestry (2015-2022). 428 2015 2016 2017 2018 2019 2020 2021 2022 Fejervarya cancrivora 2,250 (pet) 83,599,250 (cons.) [1kg = 22 indiv.] 78,498,000 (cons.) [1kg = 22 indiv.] 72,086,805 (cons.) [1kg = 15 indiv.] 4,100,850 (cons.) [1kg = 15 indiv.] 56,985,845 (cons.) [1kg = 15 indiv.] 56,985,845 (cons.) [SVL ≥ 9 cm] 56.985.845 (cons.) [SVL ≥ 9 cm] Fejervarya limnocharis 12,150; (10,000 for cons.) 3,600 (pet) 11,270 (pet) 630 (pet) 1, 080 (pet) 1,235 (pet) 1,235 (pet 1.235 (pet) Limnonectes kuhlii 540 (pet) 540 (pet) 588 (pet) 0 90 (pet) 95 (pet) 95 (pet) 95 (pet) Limnonectes macrodon 10,350; 10,000 (skin) 10,350; 9,000 (skin); 1,350 (pet) 0 0 0 0 0 0 429 430 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 Farming operations in Indonesia . - In 1982, commercial frog farming was established in 431 Indonesia only involving non -native species ( Kusrini and Alford 2006). In 1983, Lithobates 432 catesbeianus was introduced to Indonesia for the purpose of commercial farming (Susanto 433 1994), and despite Susant o’s comprehensive booklet on frog cultivation, 20 years later there 434 was no evidence that commercial breeding of this species has shown successful trends (Kusrini 435 2005). Despite government support programmes for the commercial breeding of frogs, the 436 initiative remained less promising mainly because costs of harvesting wild-caught native 437 species are lower (Kusrini 2005). Not only are high costs of breeding bullfrogs leading many 438 farms to stop breeding L. catesbeianus, the susceptibility of the species to disease is also a factor 439 (Kusrini and Alford 2006). More recent information on frog farms in Indonesia is not available 440 but examination of stable isotopes of frogs’ legs in the trade from Indonesia indicate that 441 commercial frog farms are still not established and that wild sourced populations are being 442 harvested, not farmed species (Dittrich et al. 2017). 443 444 Vietnam. - Indonesia and Vietnam represented the largest exporters of frogs’ legs in the period 445 2003-2007 (Altherr et al. 2011). In 2006 alone, Vietnam exported 573 tonnes of frog’s legs (UN 446 Commodity Trade Statistics Database 2010, in Altherr et al. 2011), while in the period 2010 -447 2019, Vietnam supplied the EU with > 8,400 tonnes frog’s legs, representing the second largest 448 supplier of frogs’ legs into the EU (EUROSTAT 2019). 449 It is challenging to determine sources of current frogs' legs from Vietnam, whether they are 450 farmed or wild -caught. According to Nguyen (2014) , the governmental regulation of frog 451 farming operations in Vietnam was meagre. Exports of frog’s legs from Vietnam to Canada are 452 based on permits documenting captive reared H. rugulosus (Gerson 2012). Quoc (2012) also 453 states that the harvest of wild sourced individuals is unstable and very difficult to estimate, thus 454 quantities for neither wild caught nor farmed frogs cannot be indicated in a “value chain 455 framework of the frog industry”. Nevertheless, forensic research could confirm frog’s legs of 456 H. rugulo sus that have been sourced from farms (Dittrich et al. 2017). Collection of wild 457 individuals is intended to replenish frog farms, still a prospect considered challenging with H. 458 rugulosus (Borzée et al. 2021). 459 460 Farming operations in Vietnam. - According to Nguyen (2000), households in the provinces 461 of Hanoi, Ha Tay, and Hai Duong have established breeding frog farms, but do not keep up 462 with national demand, and the majority of frogs for national consumption are sourced from wild 463 populations. 464 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 The many risks associated in frog farming in southern Vietnam, Tien Giang province, and Ho 465 Chi Minh City , have been highlighted by Nguyen (2014). In p articular, private e stablished 466 farms raise concerns about quality standards and risk management . Interviews with 467 representatives of various interest groups revealed that efforts to produce frogs commercially 468 often lack the necessary husbandry for successful breeding, starting with choice of location for 469 such a project, selection of suitable stock and species composition, as well as knowledge of 470 breeding, diseases, hygiene for animals and humans, environmental pollution, etc. (Nguyen 471 2014). In recent years, frog farming operations in Vietnam experienced an upswing, and the 472 country is considered the second largest producer of farm raised frogs (U.S. Soybean Export 473 Council 2019). Specially trained staff who are familiar with diseases inherent in frog farming 474 as well as the correct application of drugs/chemicals for treatment and prophylaxis are needed 475 to assure required/standardized biosecurity measures (see Thinh and Phu 2021). 476 477 478 India. - India, formerly considered the country with the largest frogs’ legs exports (Abdulali 479 1985), is discussed here only in passing. In 1985, India and Bangladesh listed their main edible 480 frog species i.e., Euphlyctis hexadactylus and Hoplobatrachus tigerinus in CITES Appendix II, 481 as a result of dramatic population declines (Oza 1990), with exports completely stopped in 1987 482 and 1989, respectively. In place of India, Indonesia stepped in and became increasingly the 483 main supplier for frogs’ legs (see Warkentin et al. 2009) in the late 1980 ’s. However, it is 484 astonishing that in 2018 , India apparently exported 5 tonnes frogs’ legs to the Netherlands, 485 despite its export ban of 1987. In this case, a confusion of the country codes (ID/IN) in the 486 EUROSTAT database cannot be ruled out but, alternatively, the export ban in India could have 487 been circumvented. Independent of this, Humraskar and Velho (2007) indicate that the trade 488 ban on frogs' legs did not have the desired effect in India. Trade data in the period 2010 -2019 489 indicates that India contributed exports of 15 tonnes into the EU (equal to 0.05% of total imports 490 into the EU [EU imports from Indonesia in the same period amounted to 74%]). According to 491 export data provided by “Seair Exim Solution”, frogs’ legs (without naming species utilized or 492 how they were sourced) originating from India were shipped to Poland via Thailand 493 (https://www.seair.co.in/frog-legs-export-data/hs-code-73023000.aspx, accessed March 2022 , 494 see Suppl. Inf. 3). 495 496 Farming operations in India. – In response to the export ban of frogs’ legs for the international 497 market imposed in 1987, initial establishment of frog farms was reported one year later. At that 498 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 time, the frog s’ leg trade was organized under the Seafood Exporters Association, who 499 proposed that the Indian government set up frog breeding centres (Vijayakumaran 1988). 500 However, it seems that a nationwide establishment of commercially operating frog farms is still 501 in its infancy in India, compared to some SE-Asian countries. In a more recently published 502 study, possibilities for establishment of commercial frog farming in Goa were explored, based 503 on the known issues of the frog trade ( e.g., wild harvest); thus to commercially produce frogs 504 would in turn “minimize illegal poaching” (see D’Silva 2015). 505 506 Turkey. - In 2017, Turkey exported 547 tonnes of frogs for the food trade (Turkey Statistical 507 Institute 2017, in Aktas et al. 2019), and according to EUROSTAT (2020), in the same year 508 >107 tonnes were imported from Turkey by France, Italy, and Spain. Between 2010-19, Turkey 509 supplied EU-countries with >1 ,593 tonnes of frog’s legs (EUROSTAT 2020). Şereflişan and 510 Alkaya (2016) note that at the national level, harvest and trade of frog’s legs in Turkey appears 511 negligible. The focus is essentially on international trade activities involving five companies 512 exporting frogs’ legs as the commodities “frozen frog s’ legs”, “chilled frog s’ legs” and 513 “processed form as live frog” to the EU and Switzerland. The authors reiterate the need for 514 commercial frog farming because the wild harvests signal overexploitation. Species of 515 economic value include four Rana spp. (R. dalmatina, R. macrocnemis, R. camerani, R. holtzi), 516 and two Pelophylax spp. (P. bedriagae, P. ridibundus) (Şereflişan and Alkaya 2016). Wild P. 517 ridibundus collected for export also include live specimens and frozen legs, 1 ,000 tonnes of 518 which are exported annually (see Alkaya et al. 2018, and references therein). 519 520 Farming operations in Turkey. - According to Dökenel and Özer (2019), P. ridibundus is 521 the primary species for EU imports, and in recent years it has been involved in farms of the 522 private and public sectors. However, the occurrence of zoonotic pathogens in frog farms 523 highlights the need for the development of sustainable frog husbandry to protect animal and 524 human health. 525 526 527 Albania. - Between 2010-2019, Albania's share of the EU market was 1% (= 590 tonnes), and 528 according to Jablonski (2011), populations of Pelophylax epeiroticus and P. shqipericus were 529 utilized both nationally and traded internationally for food. So far, however, there is no 530 conservation management plan in place for the threatened P. shqipericus (Eco Albania 2019), 531 and the species is of particular concern as offtake levels for trade purposes are considered 532 unsustainable (Gratwicke et al. 2010). 533 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 534 Farming operations in Albania. - To the best of our knowledge and research, we were unable 535 to uncover any evidence of established farms for the commercial breeding of Pelophylax spp. 536 for export, and little documentation exists of export levels . In 1996, a French businessman 537 invested in a frog farm, motivated in part by the fact that in the mid-1990s frogs’ legs in France 538 became rare (cf. above) . Mainly due to a socio-economic and political crisis, this farming 539 project failed ( https://www.discover-cee.com/roadtrip-cee-albania-how-a-french-guy-540 discovered-tirana-as-best-place-to-start-his-fintech/, accessed May 2022 , see Suppl. Inf. 3). 541 Therefore, we conclude that current export figures all refer to wild-sourced individuals. 542 543 544 Trends in EU frogs’ legs imports 545 546 Import data for the period 2010-19 were compared with data of the previous decade (see Altherr 547 et al. 2011), and three trends stand out: (1) a decrease of roughly 12.3% in EU imports of frogs' 548 legs (now 40,700 tonnes instead of 46,400 tonnes) with marked fluctuations underscoring this 549 decline (Fig. 2), (2) the role of Belgium as the highest importing country with 70% of imports 550 in the period under review (in contrast, France's import volumes decreased from 23% to 17% 551 and those of the Netherlands' from 17% to 7% ), and (3) the significant increase in the role of 552 Vietnam in export ing frogs, from 8% to 21% of total imports , with China simultaneously 553 dropping from 3% to less than 1%. 554 555 Forensic studies have shown that the species composition and labelling in Indonesia’s trade has 556 changed over recent decades (Ohler and Nicolas 2017) . Fejervarya limnocharis and 557 Limnonectes macrodon were among the most common documented species exported (Kusrini 558 2005), but F. cancrivora represents the major species in trade. 559 560 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 561 Figure 2. EU’s frogs’ legs imports (tonnes) during the period 2000-2019. Source: EUROSTAT (2012, 2021). 562 563 564 United States 565 566 While this study focuses on the EU, the current role of the United States is briefly highlighted, 567 as the US also represents a major consumer of frogs' legs (cf. Warkentin et al. 2009; Gratwicke 568 et al. 2010; Altherr et al. 2011). In the period 2015 -2020, at least four anuran species were 569 imported by the US for consumption, Lithobates catesbeianus, L. forreri, L. grylio and 570 Hoplobatrachus rugulosus (US LEMIS Database 2022). L. catesbeianus (either alive, dead, or 571 legs only) represented the major species by a large margin, predominantly supplied by Mexico 572 (mainly wild), Ecuador , and China (farmed) ( Fig. 3). This species, the American Bullfrog, 573 Lithobates catesbeianus, has also been widely introduced into Latin America and Europe fo r 574 commercial breeding purposes (Carraro 2008). In 2018, imports of H. rugulosus emerged and 575 were declared as exports from Thailand either as captive -bred or ranched, while exports from 576 Vietnam also included wild individuals. Mexico exclusively supplied the United States with 577 wild sourced L. forreri, shipped as meat or legs. In 2015 -16, the US imported more than 90 578 tonnes of meat of L. grylio all noted as captive bred (LEMIS database), but this species is native 579 to the United States ( Fig. 3). It is noteworthy that the large quantities of frogs' legs of species 580 harvested in Indonesia and eastern Europe have no sales in the USA. 581 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 582 Figure 3. Anuran species imported for the purpose of consumption into the US in the period 2015 -20, in which 583 weight (left) is compared to the number of individuals (right) to illustrate how unequally these variables are 584 aligned with each other. Source: US LEMIS database (2022). 585 586 587 National/domestic use 588 589 As can be seen in the individual IUCN Red List assessments on exploited amphibian species 590 (Suppl. Inf. 1, Fig. 2; Supp l. Inf. 4 ), many species are harvested at local/national levels for 591 consumption, medicinal, and/or spiritual purposes (e.g., Nepal 1990). Although this issue is not 592 the focus of this paper, some light can be shed on aspects of local use of frogs for consumption 593 from a conservation perspective. International trade activities can only claim to be sust ainable 594 if offtakes for national needs are also managed sustainably . This implies that monitoring of 595 harvest levels for both local/national and international consumption need to be in place (Leader-596 Williams 2002). There are numerous published examples that describe the domestic trade of 597 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 amphibians and the impact it may have on local frog populations. Species harvested for 598 consumption within national borders, and across range States, are reported for Greece 599 (Hatziioannou et al. 2022), West and Central Africa (Mohneke et al. 2009, 2010; Akinyemi and 600 Ogaga 2015; Efenakpo et al. 2015), Burundi of eastern Africa (Verbanis et al. 1993), India 601 (Pandian and Marian 1986; Ahmed 2012; Talukdar and Sengupta 2020), Nepal (Shresta and 602 Gurung 2019), PDR China (Zhang et al. 2008; Chan et al. 2014; Turvey et al. 2021), Malaysia 603 (Hardouin 1997), Vietnam ( Nguyen 2000), Mexico (Barrag án-Ramírez et al. 2021) and the 604 USA (Ugarte 2004, Ugarte et al. 2005), as exemplars of some countries/regions. The proportion 605 of national vs. international trade is of particular interest when some countries document high 606 annual exports for the international frogs’ legs industry on a regular basis, while ignoring that 607 some species have been consumed locally for decades/centuries (Angulo 2008; Onadeko et al. 608 2011; Ahmed 2012). It would not be problematic if species are traditionally consumed at the 609 local/national level and this use was deemed sustainable. However, harvest for international 610 exports (above local/traditional harvest) often means overexploitation of local populations (Oza 611 1990, and cf. species compiled in Suppl. Inf. 4). In addition, for Indonesia, it has been estimated 612 that offtakes of edible frogs on a national level are up to 142 million frogs, or seven times as 613 much as that of annual international exports (see Kusrini 2005), with no documentation of the 614 impact on wild populations, and highlighting the need for better monitoring of base populations 615 and trade. 616 617 Species diversity consumed and evaluated in the IUCN Red List 618 619 The conservation of species in trade only makes sense if the species or species complexes are 620 known. Traded species whose taxo nomic status is not known or ha ve not been verified is 621 problematic (see below). In order to get an overview of the species involved in the food trade 622 (whether at local, national , or international level), and their respective origins, the IUCN Red 623 List was filtered (Fig. 4; Suppl. Inf. 4). Regions where most species are harvested for 624 consumption are Southeast and East Asia, and it is also these regions that supply the EU market 625 with most of their frogs’ legs. Furthermore, many species are consumed in Central America and 626 (northern) South America, all of which are traded either locally, nationally, or, exported to the 627 USA (predominantly L. catesbeianus from breeding fa rms; 628 https://www.fao.org/fishery/en/culturedspecies/rana_catesbeiana/en, accessed March 2022, see 629 Suppl. Inf. 3). Interestingly, the EU is not a consumer of species from these regions. Likewise, 630 all species consumed in Africa, with the West African region forming a species focus, are 631 consumed in Africa, and the EU is not a consumer of African species (Suppl. Inf. 1, Fig. 4). 632 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 633 634 635 636 637 Figure 4. Number of species per country in trade for consumption , see Figure S2 and S3 for more detailed range 638 data and for species in international trade. Notably African species are largely consumed domestically rather than 639 exported (Suppl. Inf. 1, Figs. 2, 4). 640 641 642 643 At least 187 species of anurans and salamanders/newts are collected locally/nationally for food 644 and for the international frog s’ legs industry (Suppl. Inf. 4). According to information of Red 645 List assessments, the local/national use of 13 species (filtered by the search criteria given above) 646 was not explicitly stated , was more generally indicated (i.e., “species in the genus are also 647 commonly used for food ”), or the use has been not necessarily considered a threat (e.g., 648 Leptobrachium hainanense, IUCN SSC Amphibian Specialist Group 2020d; Suppl. Inf. 4). Of 649 the remaining 174 species, all but t wo are consumed on a local/national scale . For Lithobates 650 pipiens, only international trade is indicated (Hammerson et al. 2004), and in Ambystoma leorae 651 (IUCN SSC Amphibian Specialist Group 2020b), it was not possible to confirm if local use was 652 still present. Of all species of amphibians for which we found data , at least 20 species are 653 potentially involved in international trade activities. In some species (for example, Limnonectes 654 shompenorum, IUCN SSC Amphibian Specialist Group 2018 b), cross-border trade was 655 assumed but not substantiated. In other species, the Red List assessment notes the presence of 656 trade, i.e. , Rana amurensis (IUCN SSC Amphibian Specialist Group 2020 i). For species 657 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 indicating international trade or questioning trade across borders in some species, thus revealing 658 uncertainty in single assessments (Table 3, Suppl. Inf. 2). 659 660 Table 3. Anuran species in the European frogs’ legs trade where overexploitation and/or taxonomy is/are important 661 limiting factor(s) for sustainable commercial trade . Distribution: Information here is based on IUCN Red List 662 assessments and more recent literature . Country codes follow acronyms provided in the CITES Trade Database, 663 https://trade.cites.org/cites_trade_guidelines/en-CITES_Trade_Database_Guide.pdf; “?” next to country denotes 664 uncertainty; RLA: Red List Assessment and year when the species was most recently assessed, with ‘outdated’ 665 used to designate RLAs >10 years old ; LC: Least Concern, DD: Data Deficient, NT: near threatened, VU: 666 vulnerable; Pop. trend: population trend (: increasing; : stable; : decreasing; ?: unknown); CITES: listed in 667 either the appendices I-III, or in the annexes of the European Union Wildlife Trade Regulations (EU-WTR) A-D; 668 Information: *): Assessment involving uncertainty. Sources: IUCN (2021) and therein published Red List 669 assessments of the species concerned; Indonesian quotas - Indonesian Ministry of Environment and Forestry 670 (2022); Frost (2021) for adjusting English names, taxonomy and distribution. 671 Species Distribution RLA (year) Pop. Trend CITES / EU WTR Information on threat, trade, farming operations & exploitation levels Fejervarya cancrivora Crab-eating grass frog BN, KH, CN, IN, ID, LA, MY, PH, SG, TH, VN LC (2004, outdated)  • assumed overharvest* • utilized locally, nationally and internationally • export quota sharply increased in 2016 to more than 83 million animals for consumption and since then strong fluctuations. • 2022 harvest/export quota Indonesia: 59,985,100/56,985,845 specimens • Imported to the EU by millions as frogs’ legs • In need of taxonomic revision Fejervarya limnocharis Common Asian grass frog BD, BN, KH, CN, HK, IN, ID, JP, LA, MO, MY, MM, NP, PK, PH, SG, TW, TH, VN LC (2004, outdated)  - • harvested for human consumption, found in local and national trade (Van Dijk et al. 2004a; Nguyen 2000) • probably also in international trade • 2021 harvest/export quota Indonesia: 1,300/1,235 specimens for the pet trade, in 2015 also harvest for consumption (cf. Table 2) • cryptic species complex Fejervarya moodiei Northern Crab- eating Grassfrog CN, IN, MY, MM, PH, TH, VN DD (2004, outdated) ? - • originally thought to be known only from the type locality Manila (Luzon Island, Philippines, with unclear taxonomic validity • identified by DNA barcoding in French frogs’ legs imports (Ohler and Nicolas 2017) Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 Hoplobatrachus rugulosus Asian Rugose Bullfrog KH, CN, HK, LA, MO, MM, TW, TH, VN LC (2004, outdated)  - • large individuals may be overharvested locally • wet rice agroecosystems appear to balance the impact of exploitation • locally, nationally, and internationally traded for food • harvest of large numbers of wild individuals is ongoing, either directly to be marketed or to restock farms, e.g., in Vietnam • large numbers of frogs’ legs imported into the EU • meat is considered a delicacy in restaurants in Viet Nam (Nguyen 2000) Hoplobatrachus tigerinus Asian bull frog AF, BD, BT?, CN?, IN, MM, NP, PK; introduced to MG LC (2008, outdated)  II / B • intense harvest before the 1990s has detrimentally impacted populations (India, Bangladesh) • legal export banned in India & Bangladesh since the late1980s • utilized locally, nationally, internationally (frog leg industry) • taxonomic confusion with H. rugulosus* • species is farmed (e.g., in Vietnam or Thailand), occasionally hybridization with H. rugulosus to increase production Limnonectes blythii Blyth‘s giant frog KH?, ID, LA, MY, MM, SG, TH, VN NT (2004, outdated)  - • major threat is consumption (locally / nationally / internationally) • population decline > regional overharvest • taxonomic uncertainty > blythii complex*(van Dijk and Iskandar 2004) • relatively large species, attractive for frogs' legs trade • in the 1980s one of the dominating species in Indonesia’s exports to Europe (Le Serrec 1988) Limnonectes ibanorum Rough-backed river frog BN, ID (Kalimantan), MY (Sarawak) LC (2018)  - • large body size make species attractive for food trade • probably utilized locally and possibly also for the international frog leg trade* • life history traits make this species vulnerable to overharvest • declining populations indicate over- exploitation Limnonectes ingeri Inger’s wart frog BN?, ID (Kalimantan), MY (Sabah, Sarawak) LC (2018) ? - • large body size make species attractive for food trade • potentially exported for the frog leg industry* • locally consumed in Kalimantan and Sarawak • life history traits make this species vulnerable to overharvest Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 Limnonectes kuhlii Kuhl's Broad- headed Frog BN, CN, IN, ID, LA, MY, MM, TH, VN LC (2004, outdated)  - • cryptic taxon, species complex* • locally collected for consumption, impact on populations in China may be detrimental • declining populations indicate over- exploitation • meat is highly priced in Viet Nam (Nguyen 2000) • look-alike species of L. macrodon, included in EU imports (MNHN 2012; Ohler and Nicolas 2017) Limnonectes leporinus Giant river frog BN, ID (Kalimantan), MY (Sabah, Sarawak) LC (2018)  - • potentially exported for the frog leg industry* • regionally > overharvest of large individuals > suggesting demographic change Limnonectes macrodon Giant Javan frog ID (Sumatra, Java) LC (2017)  D • locally, nationally exploited as food; Javan populations are exploited for the international market • has been heavily harvested for the frog leg trade (Kusrini and Alford 2006), and between 1988-1991, 17 tonnes were traded for their skins and meat (Kusrini, 2017 in IUCN SSC Amphibian Specialist Group 2018a) https://www.iucnredlist.org/species/58351/ 114921568#use-trade) • according to Ohler and Nicolas (2017) the species was not traced in the international frogs’ legs market Limnonectes malesianus Malesian river frog ID, MY, SG, TH NT (2004, outdated)  - • significant decline initially reported in 2004 • overharvest is considered a major threat • collected for subsistence use and trade & utilized locally, nationally • sympatric occurrence with the larger Limnonectes blythii that is favourably collected • look-alike species of L. macrodon, included in EU imports (MNHN 2012; Ohler and Nicolas 2017) Lithobates catesbeianus American bullfrog CA, US, MX LC (2015)  - • commercially farmed for food (in non- range countries, e.g., in Thailand, Viet Nam and Brazil) • considered a pest & invasive species, e.g., in large parts of Europe, Central and South America, East and Southeast Asia • it is a possible vector of pathogens* Lithobates pipiens Northern leopard frog CA, US, PA, MX? LC (2004, outdated)  - • commercial overexploitation is considered a major threat • utilized internationally for consumption Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 Pelophylax bedriagae Bedriaga's Marsh Frog CY, EG, GR; IL; JO; LB, SY, TR LC (2008, outdated)  - • harvest/exports for food from Turkey to western Europe > considered a significant threat • large numbers are exported from Turkey (Çiçek et al. 2020; Şereflişan and Alkaya 2016) and Egypt • High extinction risk in Turkey until 2032 if exploitation level continues (Çiçek et al. 2020). • utilized local and internationally for consumption (Papenfuss et al. (2009) Pelophylax caralitanus Beyşehir frog TR NT (2008, outdated)  - • largest edible frog in Turkey; commercially overexploited for the frogs’ legs trade in France, Italy, and Switzerland (Çiçek et al. 2020; Şereflişan and Alkaya 2016) > have caused its rapid decline so that the species is now considered endangered (Erismis 2018) • High extinction risk until 2032 (Çiçek et al. 2020). Pelophylax epeiroticus Epirus water frog AL, GR NT (2019)  - • locally, nationally utilized for food • intensively was utilized in Albania for consumption, at present no evidence for excessive collections in Albania • Bd-infected populations in Albania • Potential hybridization with the sympatric P. ridibundus Pelophylax kurtmuelleri Balkan frog AL, GR LC (2008, outdated)  - • Nationally and internationally utilized for consumption • in northern parts of its native range > significantly threatened through commercial overexploitation for consumption (Uzzell et al. 2009) • another threat is considered in the unintentional introduction of commercially traded non-native water frogs Pelophylax ridibundus Eurasian marsh frog Western Europe across the Arabian Peninsula, Central Asia to Russia LC (2008, outdated)  - • harvested for educational & medical research, and food • populations extensively collected for food in Turkey (~ 1,000 t/yr) (Alkaya et al. 2018); • trade for frog legs may detrimentally impact populations in Turkey*(Çiçek et al. 2020; Şereflişan and Alkaya 2016) • frog-leg trade has led to declines in populations in eastern Asia, former Yugoslavia and possibly in Romania* • Rana (Pelophylax) kl. esculenta considered a synonym Pelophylax shqipericus Albanian water frog AL, ME, introduced to IT & HR VU (2019)  D • Nationally and internationally utilized for consumption Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 • No management plan in Albania; significantly threatened by overexploitation • Potentially threatened by unintentional

of commercially traded non- native water frogs 672 673 674 Threat status, population trends and sustainability 675 676 Among the 30 species consumed and traded locally, nationally, and/or internationally (relevant 677 for the European frogs’ legs trade), uncertainties persist in several species regarding the level 678 of exploitation (Table 3, Supp l. Inf. 2). Of all amphibian species that are consumed for food 679 and assessed in the IUCN Red List, 20 have been evaluated “Least Concern ”, one “Data 680 Deficient”, five “Near Threatened (NT)”, one “Vulnerable (VU)”, one “Endangered (EN)”, one 681 “Critically Endangered (CR)”, and nine not assessed or “Data Deficient (DD)” (Suppl. Inf. 4). 682 Importantly, most Red List assessments for these species are outdated. For example, the years 683 of assessments are 2004 ( 11 species), 2008 ( five species), 2015 ( one species), 2017 ( four 684 species), 2018 (three species), 2019 (five species) and 2020 (one species), leaving more than 685 half of these species with assessments more than 10 years old (Table 3, Suppl. Inf. 2). IUCN 686 Red List population trends indicate 18 species “decreasing”, six species “stable”, three species 687 “increasing”, and three species with an “unknown” population trend (though little data exists 688 on these populations) , indicating that many species may need to be carefully reviewed , 689 especially given the possibility of misidentification (Table 3, Supp l. Inf. 2). Of considerable 690 concern are those species that were last assessed in 2004, most notably Limnonectes blythii, 691 and. L. malesianus. These outdated assessments are further exacerbated by the fact that the 692 species are regionally overharvested for consumption as well as being involved in the 693 international trade at uncertain levels . However, of all 30 species known to be consumed , 16 694 species have special mention of harvest that might influence their conservation status. Of these, 695 12 species (Leptodactylus fallax, Limnonectes blythii, L. leporinus, L. macrodon, L. malesianus, 696 Lithobates pipiens, Pelophylax caralitanus, P. kurtmuelleri, P. ridibundus, P. shqipericus , 697 Rana amurensis, and R. chensinensis), have either “regional overexploitation-collection”, or 698 “harvest leading to declines” explicitly stated in their IUCN assessments. Another four species 699 (Fejervarya cancrivora, Hoplobatrachus rugulosus, Limnonectes kuhlii, L. microtympanum ), 700 have these same parameters as ‘presumed’ within their Red List assessments (Table 3, Suppl. 701 Inf. 2). A detrimental harvest impact is indicated for Rana dybowskii for the medicinal trade 702 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 (Kuzmin et al. 2004) and in Limnonectes grunniens and Pelophylax bedriagae, harvest for the 703 food trade is considered a significant threat. In Limnonectes ibanorum and L. ingeri, harvest is 704 considered detrimental due to the species’ unfavourable life history traits (Table 3, Suppl. Inf. 705 2). Of the 187 species filtered from the IUCN Red List that are collected for ei ther local, 706 national, or international consumption (Suppl. Inf. 4) , assessments of population trends since 707 2004 to 2020 clearly show population declines as well as the upgrading of threat categories 708 over the study period (cf. Figs. 5, 6). Uncertainties outlined in this review remain unevaluated, 709 and a resolution of these for individual species assessments would likely influ ence the 710 categorisation of the threat status and population trends. 711 712 713 Figure 5. Relationship of Red List status (bars) and population trend (lines) of 187 amphibian species globally 714 utilized for consumption that have been assessed between 2004 and 2020. Source: IUCN (2021); cf. Suppl. Inf. 715 4). 716 717 0 5 10 15 20 25 30 35 40 45 50 2004 2008 2013 2014 2015 2016 2017 2018 2019 2020 DD LC NT VU EN CR unknown stable decreasing increasing Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 718 719 Figure 6. Population trends assessed in 187 amphibian species, consumed for food, in 10 assessment periods 720 between 2004-2020 (cf. Suppl. Inf. 4). 721 722 CITES species and their trade 723 724 The Convention on International Trade in Endangered Species of Wild Fauna and Flora 725 (CITES) currently lists 220 amphibian species in their a ppendices, equating to ca. 2.6% of all 726 amphibian species (8,386 spp.; Frost 2021) recognized by science. The CITES trade database 727 (https://trade.cites.org/, accessed January 2022 , see Suppl. Inf. 3) merely lists seven anuran 728 species that are traded for the purpose of consumption (Table 3). Nonetheless, the majority of 729 species involved in the frogs’ legs trade are not listed in the appendices of CITES (cf. Table 3, 730 Suppl. Inf. 2, 4), and cannot refer to CITES trade data in order to obtain approximate 731 information on species volumes traded per annum or query specific trends. 732 All seven CITES listed anuran species are utilized on a local/national scale and three (i.e., 733 Pelophylax shqipericus, Limnone ctes macrodon and Hoplobatrachus tigerinus), are involved 734 in the international frogs’ legs trade (cf. Table 4) as well. All seven species have been evaluated 735 in the IUCN Red List and three other species, (i.e., Conraua goliath, Laotriton laonensis and 736 P. shqipericus) are not listed in the appendices of CITES but appear in the annexes of the 737 European Wildlife Trade Regulations (EU WTR). All but two of these species have a 738 decreasing population trend and two species were last assessed in 2004 and 2008. 739 740 0 10 20 30 40 50 60 2004 2008 2013 2014 2015 2016 2017 2018 2019 2020 decreasing stable unknown increasing Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 Table 4. Seven anuran species listed on the appendices of CITES (I-III) and annexes of the European Wildlife 741 Trade Regulations (A-D) that are currently known to be consumed locally/nationally and those utilized within the 742 international frog s’ legs industry. Country codes follow acronyms provided in the CITES Trade Database ( 743 https://trade.cites.org/cites_trade_guidelines/en-CITES_Trade_Database_Guide.pdf); RLA: Red List Assessment 744 and year, when the species was assessed, LC: Least Concern, VU: vulnerable, EN: endangered, CR: critically 745 endangered; Pop. trend: population trend ( : stable; : decreasing). CITES: listed in either the appendices I -III, 746 or in the annexes of the European Union Wildlife Trade Regulations (EU-WTR) A-D; Sources: IUCN (2021) and 747 therein published Red List assessments of the species concerned (https://www.speciesplus.net). 748 Species Distribution RLA (year) Pop. Trend CITES & EU-WTR (year when listed) Consumption & Trade Calyptocephalella gayi Helmeted water toad CL VU (2018)  III (2011) C (2012) National, international (likely only pet trade) Conraua goliath Goliath frog CM, GQ, GA? EN (2018)  B (1997) National Euphlyctis hexadactylus Indian green frog BD, IN, NP?, LK LC (2004)  II (1985) B (1997) National Hoplobatrachus tigerinus Asian bull frog AF, BD, BT?, CN?, IN, MM, NP, PK LC (2008)  II (1985) B (1997) National, international Limnonectes macrodon Giant Javan frog ID (Sumatra, Java) LC (2017)  D (2009) National, international Pelophylax shqipericus Albanian water frog AL, ME VU (2019)  D (2009) National, international Telmatobius culeus Titicaca water frog BO, PE EN (2019)  I (2017) A (2017) National, international 749 750 Four species are listed in CITES App. II, and one in CITES App. III that are consumed either 751 locally/nationally and/or internationally traded for consumption, while another four species are 752 only listed in the annexes of the EU-WTR (Table 4, Suppl. Inf. 4). 753 754 1. Calyptocephalella gayi. - Since 2011, the species is listed on CITES App. III in Chile. In 755 2012-2016, reported exports of 114 live individuals were recorded at the same time that 550 756 live individuals were imported. In 2012, 14 live individuals were seized in Japan, and the 550 757 animals were sourced from captivity in Chile and imported by the US and Japan. International 758 trade for the purpose of consumption is not explicitly documented, despite the fact that the 759 species is nati onally and internationally involved in the food trade ( IUCN SSC Amphibian 760 Specialist Group 2019a). 761 2. Conraua goliath. - This species is not listed in the appendices of CITES but in Annex B of 762 the EU -WTR. H owever, eight transactions 1998 - 2019 of wild sou rced individuals w ere 763 documented in the CITES trade database. All exports were from Cameroon, with 19 live 764 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 individuals commercially exported by Cameroon and 65 individuals claimed as commercial 765 imports by EU importing countries. In 2004, Cameroon exported 199 specimens to the United 766 States for scientific purposes. International trade for the purpose of consumption is not 767 documented despite the species being locally/nationally consumed ( IUCN SSC Amphibian 768 Specialist Group 2019b). 769 3. Euphlyctis hexadactylus . – International trade has been documented since 1985 (date of 770 CITES listing), with India as the major supplying country until 2006, documenting the export 771 of roughly 1,215 tonnes of meat, while importing countries documented the import of ca. 2,588 772 tonnes meat (https://trade.cites.org, see Suppl. Inf. 3). Within the same period, Belgium and the 773 United States imported another ~0,7 tonnes meat indicating India as the country of origin. As 774 of March 2018, India ban ned the commercial export of wild harvested specimens 775 (https://www.speciesplus.net/species#/taxon_concepts/4945/legal, see Suppl. Inf. 3). 776 4. Hoplobatrachus tigerinus. – Exports are documented since 1985 (date of CITES listing) and 777 transactions have been reported until 2019 . However, the largest quantities were shipped in 778 2007. Analysis of trade data of this species is particularly challenging because quantities are 779 misleadingly indicated and no n-range States of the species export large quantities, including 780 meat of wild sourced individuals (e.g., from Vietnam and Madagascar , documented in the 781 CITES trade database). 782 5. Limnonectes macrodon. - This species is not listed in the appendices of CITES but in Annex 783 D of the EU-WTR. However, a single transaction was documented in the CITES trade database. 784 In 2016, Germany reported the import of two live individuals from Indonesia, sourced from the 785 wild. The species is int ensively involved in the local, national , and international food trade 786 (IUCN SSC Amphibian Specialist Group 2018a). It is remarkable that the Annex D records do 787 not reflect an intense EU import of frogs’ legs officially labelled as “ Limnonectes macrodon”, 788 as noted by Dittrich et al. (2017), since this is almost a certainty. 789 6. Pelophylax shqipericus. - This species is not listed in the appendices of CITES but is in 790 Annex D of the EU -WTR since 2009 because there was concern regarding the numbers 791 imported into the EU, with monitoring of this trade warranted, and a distinct lack of a rigorous 792 non-detriment finding (https://www.speciesplus.net/species#/taxon_concepts/5193/legal, see 793 Suppl. Inf. 3). 794 7. Telmatobius culeus. - Commercial trade of the species was suspended in 2017, with listing 795 in CITES Appendix I and EU-WTR Annex A. In the period 2010-2022, the CITES trade 796 database indicates only two transactions: the import of 20 live individuals to Canada, and 150 797 live animals to the UK. In both cases, the animals were destined for zoos and sourced as 798 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 “farmed” from the USA. According to the IUCN SSC Amphibian Specialist Group (2020j), it 799 is estimated that >15,000 animals/year are used to prepare frogs' legs. 800 801 802 Disease, pesticides and veterinary drug residues, genetic pollution 803 804 The farming and regional/international trade activities involving amphibian species for 805 consumption purposes is associated with numerous risks. Here, we outline these more 806 specifically. 807 808 Disease. - Evidence clearly demonstrates that the commercial trade of amphibians infected 809 with pathogens contributes to the spread of diseases within and between countries, on a global 810 scale, and involves species traded for food (Fisher and Garner 2007; Miller et al. 2011; 811 Rodgers et al. 2011; Olson et al. 2013; O’Hanlon et al. 2018). 812 The intercontinental spread of two fungal diseases , Batrachochytrium dendrobatidis (Bd) and 813 B. salamandrivorans (Bsal), has led to the decline of more than 500 amphibian species and 814 currently more than 1000 species are known to be infected by one of the se two emergent 815 infectious diseases (Scheele et al. 2019; Monzon et al. 2020). The spread of infectious diseases 816 may also be exacerbated by global warming (e.g., Lampo et al. 2006; Bosch et al. 2007; Seimon 817 et al. 2007). With new climate projections, models predict expansion of Bd into new areas both 818 in higher altitudes and elevations (Xie et al. 2016) which might impact with current farms in 819 those areas. Other pathogens (e.g., ranaviruses) also could expand their range as a consequence 820 of climate change (cf. Price et al. 2019), highlighting the need for better biosecurity measures 821 in the commercial trade. 822 Interactions betwee n ecological factors and amphibian-pathogen dynamics are extremely 823 complex and pose major challenge s for management decisions (Lips 2016; Bienentreu and 824 Lesbarrères 2020). The commercial farming of anuran species poses challenges in terms of 825 hygiene and proactive biosecurity and disease prevention measures. In the past (Kanchanakhan 826 1998; Zhang et al. 2001; Mauel et al. 2002; Weng et al. 2002), as well as more recently (Gilbert 827 et al. 2013; Aktaş et al. 2019), many bacterial, viral, and fungal pathogenic diseases have been 828 reported affecting mass-produced farmed frogs. A Mycobacterium-associated disease has been 829 detected in Hoplobatrachus rugolosus animals in Vietnam that may pose a public health risk 830 and highlights the need for improved biosecu rity measures in the breeding and trade of frogs 831 (Gilbert et al. 2013). Already in the 1970s (Andrews et al. 1977) and 1980s , Salmonella was 832 detected in samples of frozen frogs' legs. Out of 304 samples, Salmonella was detected in 121 833 samples (39.8%), with 25.4% from India and 51.5% of the positive samples from Indonesia. In 834 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 France, frogs' legs are a significant source of Salmonella and are undoubtedly a source of 835 multiplication (Catsaras 1984). In a long-term study 1990-1998, Salmonella of the serotype C1 836 was isolated of domestically available frogs’ legs from New York State previously imported 837 from Indonesia (Heinitz et al. 2000). 838 Exports of Pelophylax [Rana] esculentus from Albania for consumption to foreign markets also 839 revealed Salmonella, Vibrio cholerae, Listeria spp. and Aeromonas spp., the latter two being 840 clearly more common (Vergara et al. 1999). 841 One internationally commercialised species for consumption is particularly striking: the North 842 American bullfrog (Lithobates catesbeianus), a known vector of ranavirus detected in cultured 843 specimens in South America n exports to the USA (Galli et al. 2006; Miller et al. 2007; 844 Schloegel et al. 2009), and the fungal disease Bd (Garner et al. 2006) translocated within 845 farming operations in South America (Mazzoni et al. 2003) and in China and Singapore, where 846 cross-infections from farmed individuals to native amphibians have been suggested (Bai et al. 847 2010; Gilbert et al. 2013). The danger that L. catesbeianus, as a carrier of Bd, can threaten naïve 848 populations of other amphibian species has been emphasised by Rödder et al. (2013) who 849 clearly highlight the link between the spread of Bd and bullfrogs. Also, novel chytrid genotypes 850 have been identified and linked to the trade with L.catesbeianus (Schloegel et al. 2012). 851 However, with regard to live imports of L. catesbeianus into the EU since 2016, the species is 852 subject to a stricter legal regime, an d has therefore been deleted from Annex B (http://eur-853 lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32016R2029&from=EN, accessed 854 March 2022, see Suppl. Inf. 3); in 2013 and 2014 L. catesbeianus listing in Annex B referred 855 to the import of live specimens. 856 Two more species involved in the food trade (see Table 3, Suppl. Inf. 2) have tested Bd+: 857 Lithobates megapoda (Frías-Alvarez et al . 2008) and Albanian populations of Pelophylax 858 epeiroticus (Vojar et al. 2017; IUCN SSC Amphibian Specialist Group 2020g). 859 Challenges with regard to the spread of diseases with live animals intended for the food trade 860 are multi-layered. On one hand, trade of live amphibians poses a potential risk of cross-infection 861 into naïve wild populations via escape and contamination through waste water disposal. On the 862 other hand, commercial breeding farms also pose risks of escaped animals and disposal of water 863 and housing materials that can be carriers of pathogenic diseases. This demonstrates two 864 predominant pathways for spreading pathogenic diseases : translocation and commercial 865 farming operations (cf. Jaÿ et al. 2019; Travis et al. 2011). To what extent processed frogs' legs 866 pose a hygiene risk (see issues described above) appears to be a largely understudied topic . 867 However, skinned and frozen meat seems to present less risk with regard to the spread of 868 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 infectious diseases such as Bd (Gratwicke et al. 2010). In the case of Salmonella, however, 869 more care is needed to avoid contamination (Grano 2020) in any substrate, individual, or tissue, 870 frozen or fresh. 871 872 Pesticide and veterinary drug residues in wild and farmed frogs. - We cannot provide 873 comprehensive information on residues and effects (on the end consumer) of toxins used in 874 regional agriculture and ingested indirectly (via the nutrient cycle) by frog species. Nor are we 875 able to tease apart the effects of ingestion of veterinary cocktails of commonly used antibiotics, 876 i.e., oxytetracycline and doxycycline (see Nguyen and Tran 2021) used in commercially farmed 877 frog species for international consumption. Instead, we would like to illustrate existing health 878 risks for humans as end consumers with a collection of circumstantial evidence. Many of the 879 studies mentioned provide initial results of research projects, but many more follow-on studies 880 do not exist due to the lack of interdisciplinary studies, opacity of supply chains, and distances 881 and conditions of transportation of fully or partially processed frogs' legs. 882 Here we address the questions : (1) What are the most common habitat types and species that 883 are captured for the international consumption trade?, (2) How are these habitats managed with 884 regard to the use of pesticides , herbicides, and other agricultural chemicals? , (3) Do these 885 agrochemicals negatively affect faunal assemblages and their ecosystems? , (4) Are these 886 chemicals detectable in imported frogs' legs?, (5) Have veterinary drug residues been detected 887 in aqua-cultured frog legs?, and finally, (6) Is there evidence that the consumption of frog legs 888 contaminated with medicinal or pesticide residues can be hazardous to human health? 889 890 Probably the most common frog involved in the global frog s’ legs industry is Indonesian F. 891 cancrivora (75% of reported species). This species is considered the most abundant frog species 892 inhabiting rice fields in Indonesia (see Kusrini 2006, and references therein). 893 It appears that Javan populations of F. cancrivora are predominantly harvested for the 894 international frog leg trade ( cf. Kurniati and Sulistyadi 2017). The intense use of pesticides is 895 prominent in Indonesia, and according to Ardiwinata et al. (2018), highest pesticide residues 896 are found in Central Java. Quality of freshwater in terms of pesticide input and hence the 897 contamination of semi-aquatic communities (e.g., amphibians), in rice plantations on Java, is 898 problematic (Iskandar 2014). Disruption of the food web has led to an increase in populations 899 and population densities of the brown locust ( Nilaparvata lugens ) which damages rice 900 plantations and causes significant crop losses. West and Central Java farmers therefore feel 901 compelled to use more pesticides and create their own mixtures of these chemicals (Prihandiani 902 et al. 2021). The use of pesticides in various agro -ecosystems (incl. freshwater ecosystems) 903 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 negatively affects food webs (see Relyea and Hoverman 2008), shifts species composition and 904 abundance, and leads to severe declines of some species in these systems (cf. Pingali and Roger 905 1995 and ref erences therein). Furthermore, exposure of frogs to pesticides also leads to an 906 increased risk of infection due to the weakening of the immune system (Kiesecker 2011) . 907 According to Quaranta et al. (2009), absorption of herbicides such as atrazine through the skin 908 of amphibians is "300 times higher than in mammals". Herbicides were found to negatively 909 affect larval stages of F. limnocharis populations in Taiwan (Liu et al. 2011) and health status 910 was likewise reduced in populations of F. limnocharis in pesticide-contaminated rice fields (as 911 residues in soil and direct expos ure) in the Western Ghats and Kerala (India) (Hedge and 912 Krishnamurthy 2014; Kittusamy et al. 2014). A study by Kittusamy et al. (2014) also found 913 pesticide residues in F. limnocharis and H. crassus that led to malformations in some 914 individuals. However, other pathogenic influences besides pesticide s as well as synergistic 915 effects of pesticides are also considered to be causing these malformations (also see Wijesinghe 916 2012). The harmful effects of pesticides on anuran species have been confirmed in populations 917 of Pelophylax perezi in France as well (Mesléard et al. 2016). 918 919 The question now arises whether pesticide residues or other toxins have been detected in traded 920 animals or parts thereof for commercial consumption by humans. Information on the potential 921 of bioaccumulation has rarely been analysed and more work is needed (Mani et al. 2021) . It 922 was found that some populations of pig frogs (Lithobates [Rana] grylio) harvested in south-923 eastern United States (for local consumption ) contain a high level of mercury (Ugarte et al. 924 2005). According to a study performed by Turnipseed et al. (2012), drug residues could be 925 detected in aqua-cultured samples of frogs’ legs. The combination of different residues in the 926 examined frogs’ legs was striking, and lead to the conclusion that varying chemotherapeutic 927 agents (including those harmful to human, e.g., chloramphenicol; Turnipseed et al. 2012) are 928 apparently used indiscriminately in frog aquaculture. More recently , a study highlighted a 929 variety of antibiotics applied at commercial frog aquaculture facilities in Viet Nam and 930 uncontrolled dosage of drugs (Nguyen and Tran 2021). 931 The question of whether pesticide residues and other potentially toxic substances in frogs that 932 are imported into the EU have been monitored could not be determined in the course of this 933 work. This in itself is shocking, and in view of the situation in exporting countries and the lack 934 of transparency and management in the application of agrochemicals and veterinary medicinal 935 substances within commercial farms, we strongly recommend that this monitoring become an 936 urgent near-future task for importing countries. 937 938 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 Genetic pollution . - In 2010 , Holsbeek and Jooris reported that in the preceeding decade, 939 humans translocat ed individuals of Pelophylax spp. either unintentionall y (e.g., escaped 940 animals from nurseries and markets) or intentionally (e.g., for stocking garden ponds and for 941 local culinary harvest) almost everywhere they exist . A study conducted by Duresnes et al. 942 (2018) showed that the presence of individuals of the Pelophylax ridibundus species complex 943 derive from varying genetic lineages that correlate with registered frog leg industry imports in 944 Switzerland, implying that individuals were also released/translocated for commercial purposes 945 (regionally and internationally), revealing hybridisation events in se veral cases. Thus, the 946 harvest of East European frog species involved in the frog -leg industry and subsequent 947

into western Europe ha s led to genetic pollution and threatens to damage their 948 native congeners (Dubey et al. 2014; Dufresnes et al. 2018). It has also been suggested that the 949

of the invasive P. kurtmuelleri from the southwestern Balkans to southern Italy 950 was also due to the frogs’ legs trade (Bisconti et al. 2019). 951 Another example that does not explicitly address commercial trade of frogs' legs in the EU, but 952 names taxa that are traded regionally for this purpose (see also Table 3), is the unregulated trade 953 of frogs for ornamental ponds in Belgium. This has led to non-native Pelophylax spp. displacing 954 native species or hybridising with them and is due to inefficient legislation at national and EU 955 level, lacking regulation for the import of potentially invasive species (Holsbeek et al. 2010). 956 Furthermore, the commercial frog leg industry already contributes to the unintentional release 957 of specimens into naïve habitats and displacing native species (e.g., Ribeiro et al. 2019 and 958

cited therein ). Amongst these myriad species are American bullfrogs ( L. 959 catesbeianus), which, including their larval stages , detrimentally impact many other anuran 960 species (cf. Kiesecker et al. 2011). Escapes of Hoplobatrachus rugulosus (originating from 961 Thailand, referred to as "Thailand tiger frogs") have been reported, and are kept in Chinese frog 962 farms and may lead to hybri disation with Chinese populations of H. rugulosus (referred to as 963 "Chinese tiger frogs") (Yu et al. 2015). The authors suggest improving management of these 964 farms to avoid further release of Thailand tiger frogs because a cryptic species complex is 965 suspected, and thus species may unwittingly be driven extinct because they have not been 966 recognised. These issues are also pertinent for other amphibian species complexes. F or 967 example, in the case of the Chinese Giant salamander, recent assessments show that mult iple 968 species exist across China, but farming and release of one of these species outside its range has 969 virtually eliminated other Chinese Giant salamander species (Turvey et al. 2018; Yan et al. 970 2018; Lu et al. 2020). 971 972 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 Taxa traded with uncertain taxonomic status 973 974 The use and trade of species in their country of origin and whose taxonomic status is uncertain 975 affects at least four species involved in the international frogs’ legs industry as well. Among 976 these, three are designated as species complexes (i.e., more than one species under one current 977 scientific name) and species with unresolved taxonomy in IUCN Red List assessments . They 978 are: Fejervarya cancrivora, Hoplobatrachus tigerinus and Limnonectes blythii. There are many 979 other species complexes , wherein the taxonomy is extremely complex , and uncertainties are 980 even more fraught with problems. In Fejervarya moodiei , for example, it remains unclear 981 exactly to what free-living population this species should be assigned. In another two species 982 (Limnonectes grunniens and L. kuhlii), where impact of international trade for frog legs has not 983 been explicitly ascertained within their assessments (but is very high) , taxonomy remains 984 unresolved. In these species of Limnonectes, both their geographic range and number of cryptic 985 species ‘hiding’ under one scientific name are still unclear (IUCN SSC Amphibian Specialist 986 Group 2020 e; van Dijk et al. 2004 b). To what extent populations assigned to L. ku hlii are 987 involved in the international frog leg industry is not indicated in the species’ Red List 988 assessment. Since all but two assessments are from 2004, H. tigerinus in 2008 and L. grunniens 989 in 2019 ( Table 3, Suppl. Inf. 2), recent research findings sometimes provide more clarity 990 regarding the unsettled taxonomy of aforementioned species/taxa. 991 992 Of the three “species” that clearly represent complexes of many different species, we highlight 993 what is known here, but reiterate that the dearth of data is staggering, considering that these are 994 the most economically valuable species in terms of the known trade in commercial frogs’ legs. 995 996 Fejervarya cancrivora . - An initial molecular analysis, six years after F. cancrivora was 997 evaluated in the IUCN Red List (Yuan et al. 2004), revealed three geographically distinct 998 clades/subclades: one confined to Bangladesh, Thailand , and the Philippines; another 999 representing Malaysia and Indonesia (Greater Sundas) ; and the remaining one from Sulawesi 1000 (incl. one population in southern West Java, as a result of human introduction) (Kurniawan et 1001 al. 2010). A second study by Kurniawan et al. (2011) examined the species’ morphological 1002 traits and crossing experiment s through artificial insemination that resulted in three distinct 1003 taxa: 1) populations of West Java , peninsular Malaysia, and Bangladesh assigned to F. 1004 cancrivora, 2) populations from the Philippines and China previously referred to as F. moodiei, 1005 and 3) a new species endemic to Sulawesi. However, findings of a more recent study delimit F. 1006 cancrivora to Thailand, peninsular Malaysia, and Indonesia (Sumatra, Kalimantan, western and 1007 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 central Java, Bali), with introduced populations occurring in Papua New Guinea and Guam 1008 (Yodthong et al. 2019; and refs therein). According to Dubois and Ohler (2000) F. moodiei was 1009 not allocated to any known natural population. However, almost 20 years later, the species was 1010 validated and confirmed from mainly coastal areas of South Asia (eastern India, Andaman, and 1011 Nicobar Isl.,), East Asia (southern China), and Southeast Asia (Vietnam, Thailand, Myanmar, 1012 Malaysia, and the Philippines [Luzon Isl.]) (Yodthong et al. 2019; and references therein). 1013 1014 Clear taxonomy is the foundation of efficient and sustainable species conservation, and so is 1015 the naming of the species or parts thereof that are to be traded. Examination of 209 frozen frogs’ 1016 legs sold in supermarkets in France listed exclusively as Limnonectes [Rana] macrodon (based 1017 on product labelling), revealed that almost all (206 of the 209 or 98.6%) were in fact legs of F. 1018 cancrivora, and only 2 (0.96%) could be attributed to L. macrodon, while one sample was 1019 revealed to be F. moodiei (Ohler and Nicolas 2017). Such forensic studies clearly highlight the 1020 importance of competent species identification, especially when it comes to evaluating current 1021 use in terms of sustainability, as the lack of such information precludes accurate monitoring of 1022 trade as a consequence of misidentification . Many more members of both the Dicroglossidae 1023 and Ranidae families are commercially involved in the frogs’ legs industry, and their taxonomic 1024 status remains blurry at best. 1025 Hoplobatrachus tigerinus . - in their Red List assessment , the authors indicate H. tigerinus 1026 reflects a species complex including an unknown number of morphologically very similar 1027 (cryptic) species (Padhye et al. 2008). This was confirmed by Hasan et al. (2012). Most recent 1028 research identified populations of H. tigerinus from Pakistan and Bangladesh as genetically 1029 identical to those from Nepal (Khatiwada et al. 2017), but genetically different from Indian 1030 populations (Akram et al. 2021). Clearly, this is a complex issue with much more clarity needed 1031 before the trade becomes sustainable. 1032 Limnonectes kuhlii. - the taxonomic status of L. kuhlii associated with the species’ currently 1033 known distribution range has been described as particular ly uncertain within the Red List 1034 assessment (van Dijk et al. 2004b), and many more new taxa have been assumed with some 1035 revealing range-restricted distributions. Following genetic research, this complex now includes 1036 a minimum of 22 “ distinct evolutionary lineages” (McCleod 2010). Again, the real biological 1037 entities that are involved in the commercial frogs’ legs trade clearly are not well understood, 1038 much less studied to the degree to which we can provide realistic plans or guidelines for 1039 sustainable trade. 1040 1041 1042 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 Ecological impact of trade 1043 1044 Sixteen of the 30 anuran species listed in Table 3 and Suppl. Inf. 2, (i.e., Fejervarya cancrivora, 1045 Limnonectes blythii, L. grunniens, L. kuhlii, L. leporinus, L. macrodon , L. malesianus , L. 1046 microtympanum, Lithobates pipiens, Pelophylax bedriagae, P. caralitanus, P. kurtmuelleri, P. 1047 ridibundus, P. shqipericus, Rana amurensis, and R. chensinensis) have commercial (regional) 1048 overharvest/overexploitation as a significant/main threat (both for food) indicated as assumed 1049 or known threat in their respective Red List Assessments . Species that were previously 1050 intensively exploited were not included (i.e., Hoplobatrachus tigerinus and Leptodactylus 1051 fallax), as former legal trade was banned in the mid -1990s (Padhye et al. 2008), and other 1052 utilization was banned since the 2000s (IUCN SSC Amphibian Specialist Group 2017). It is 1053 important to note that the conservation status of most species involved in the food trade (Table 1054 3; Suppl. Inf. 2) is not up to date (53% or 16 species last assessed 2004-08), and reassessments 1055 of some species might indicate overexploitation, adding more species where commercial 1056 exploitation for international consumption is considered unsustainable. 1057 1058 Prior to export for international trade, a considerable number of live animals die on arrival to 1059 the processing facilities . For Indian exports , this loss has been estimated at 10 -20%, in 1060 Indonesia it is 40-50 % because quality is not sufficient for export and some frogs are killed 1061 prior to being exported (Niekisch 1986 , and references therein ). Information on pre -export 1062 mortality rates in countries of origin were not easy to obtain within the scope of our study. 1063 These figures are also relevant when it comes to evaluating the ecological impact of harvest , 1064 and more clear understanding of how these losses could be lowered wo uld benefit both the 1065 people involved in the trade and the frog populations. 1066 1067 Initial reports on the sustainability of this trade were published more than 20 years ago, however 1068 large-scale ecological studies to assess o fftake rates and their sustainability appear severely 1069 lacking. Here, we highlight studies that indicate amphibian declines associated with harvest for 1070 the food trade both regionally and internationally. Historically, overharvest was detected in 1071 Californian populations of Rana aurora draytonii (Jennings and Hayes 1985). In Florida , 1072 harvest regimes of Lithobates [Rana] grylio affect population structure and survival rates 1073 (Ugarte 2004). The increasingly intense regional harvest of frogs in West Africa, particularly 1074 in Nigeria where trade has moved across borders (e.g. , Benin), clearly demonstrates 1075 overexploited species and populations (Mohneke 2011) . The harvest of populations of 1076 Quasipaa spinosa in Hong Kong is also detrimental to populations in the long -term (Chan et 1077 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 al. 2014). Below, we highlight case studies that report on overexploitation of 1078 species/populations from Indonesia and Turkey involved in the international commercial trade. 1079 1080 Indonesia. – In 2005, Kusrini noted that c urrent harvest levels of Fejervarya cancrivora and 1081 members of the F. limnocharis -iskandari complex (F. iskandari was separated from the F. 1082 limnocharis complex through allozyme data; Veith et al. 2001) appear to be sustainable, 1083 however offtake of Limnonectes macrodon may detrimentally affect populations more than 1084 those of F. cancrivora. 1085 The majority of frog hunt ers in East Java reported that the number of harvested frogs has 1086 decreased and this was also perceived by middlemen (in West and East Java), and exporters, 1087 who argued that depending on the season, supplies were sometimes scarce (Kusrini and Alford 1088 2006). To explain declines in frog populations, hunters reported a combination of three reasons, 1089 “1) increasing numbers of harvesters; 2) increasing numbers of middlemen, allowing 1090 harvesters to go to other middle -men; and, 3) habitat change, as more rice fields have been 1091 developed for other uses” (Kusrini and Alford 2006). However, overharves t synergistically 1092 promotes decline of amphibian populations happening simultaneously from habitat loss and 1093 degradation, pollution, disease, and invasive exotic species (Kusrini 2007). 1094 Several regional field studies have been conducted in Indonesia to assess population densities 1095 of frog species involved in the food trade, and these clearly show these synergistic effects. In a 1096 20x20m paddy field in West Kalimantan, the density of F. cancrivora was measured at 1.01 1097 individuals/m2 (Saputra et al. 2014). According to Iskandar (2014), populations of Limnonectes 1098 blythii in West Sumatra have largely been decimated by export of frog s’ legs (though once 1099 again monitoring is absent) and hence the harvest of populations has shifted to other provinces 1100 like Riau, Jambi, and South Sumatra. The Karawang district, on the other hand, is the largest 1101 producer of frog meat in West Java. In order to determine the sustainability of hunted 1102 populations of F. cancrivora, in May 2016 an approximately 10-day population survey wa s 1103 conducted in a rice field in eastern Karawang. Average density for juveniles was 0.33 1104 individuals/m2, 0.04 for subadults, and 0.005 for adults. In contrast, average density in watered 1105 paddy fields was 0.89 individuals/m2 for juveniles, 0.08 for subadults, and 0.01 for adults 1106 (Kurniati and Sulistyadi 2017). Depending on the season and the status of the rice fields (state 1107 of cultivation, amount of water), an average of 3 -10 kg of adult frogs can be caught per night 1108 since frog hunters have an agreement not to capture juveniles and subadults to maintain viable 1109 breeding populations (Kurniati and Sulityadi 2017) . Populations of F. cancrivora in the rice 1110 fields of the Karawang region are considered unhealthy, most likely due to unsustainable 1111 exploitation, and setting export quotas for frogs’ legs should be done with care (Kurniati and 1112 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 Sulityadi 2017). The main threat to F. cancrivora is the large-scale harvest for trade and 1113 consumption, although habitat destruction and degradation also play a role and further impair 1114 population recovery following collection of individuals from the wild (Amin 2020). 1115 Limnonectes macrodon is also regionally impac ted and preferred for their better taste 1116 (compared to F. cancrivora; Kusrini and Alford 2006) . In addition, L. macrodon has slower 1117 reproduction rates, [~1000 eggs per clutch (Iskandar 1998) as opposed to >18,000 eggs in one 1118 spawning for F. cancrivora (Saputra et al. 2014)], and is therefore more vulnerable to 1119 overharvest. According to Ohler and Nicolas (2017), populations of L. macrodon are in rapid 1120 decline. 1121 1122 Turkey. – Overharvest of frog populations in Turkey (intended for export to France, Italy, 1123 Greece, Spain, Switzerland, and Lebanon) has been reported by Şereflişan and Alkaya (2016), 1124 who note that individual frogs had a reduced weight due to overharvest, and that had a negative 1125 effect on the export value. Regional overharvest in Turkey has been shown for Pelophylax 1126 caralitanus populations in southwestern Anatolia (Erismis 2018). 1127 A very recent study, by Çiçek and others in 2021, on the sustainability of Anatolian water frogs, 1128 is by far one of the most comprehensive studies to analyse commercial trade in frogs’ legs for 1129 the EU market. In 2013-2015, >13,000 Pelophylax spp. (cf. Red List assessments of Pelophylax 1130 bedriagae, P. caralitanus, and P. ridibundus) from two regions were tagged for population and 1131 density estimation. A population viability analyses was conducted over a 50-year period based 1132 on catch and export data from Turkey. If this trade were to continue at the same harvest rate, 1133 extinction risk would be 90% in 50 years, affecting two to five species of the Pelophylax species 1134 complex (Çiçek et al. 2021, and references therein). Accordingly, a reduction of harvest rates 1135 would be advisable in order to be able to ensure the viability of these frog popu lations and a 1136 long-term source of income for the harvesters/frog catchers (Çiçek et al. 2021). 1137 1138

1139 1140 During the course of this study, it became clear just how difficult it is to obtain concrete data 1141 on the current international trade in frog legs. Specifically, relevant data are scattered across 1142 different unconnected databases (e.g., national databases, FAO, EUROSTAT , or 1143 information/services that can only be obtained/provided via payment, e.g. , Infofish 1144 International (http://infofish.org/v3/, Suppl. Inf. 3). Another problem is data reliability with the 1145 competence of sourcing agencies and institutions having conflicts of interest and little expertise 1146 in frog identification. While the USA primarily imports live frogs and frog products for human 1147 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 consumption originating from frog farms, frogs and their processed legs imported into the EU 1148 are mostly sourced from the wild. The EU trade also includes far more species than are officially 1149 declared, potentially including many cryptic species of conservation concern. 1150 Our findings highlight the central role of the European Union as the main importer of frogs’ 1151 legs derived from wild individual anuran populations, the urgent need for stricter trade 1152 regulations, better monitoring and data integrity to prevent further declines of wild frog 1153 populations, and help create a more sustainable commercial trade. 1154 1155 1156 A long road to EU accountability 1157 The high uncertainty of the assumed number of individual frogs within total imports throughout 1158 the study period impressively illustrates the opacity of the trade. A ctual harvest numbers 1159 imported into the EU for annual consumption remain unknown and very difficult to quantify . 1160 This is undoubtedly due to the fact that they are non-CITES species and thus international trade 1161 data (species/volumes) remain undocumented. L isting species in the appendices of CITES is 1162 justified when international trade poses a severe threat to the conservation status of a species. 1163 The scientific authority of a CITES member state must review the harvest/export for Appendix 1164 II in terms of compatible offtake numbers/quotas in order to maintain the species ’ ecological 1165 function in its native habitat (https://cites.org/eng/disc/text.php#IV, accessed May 2022, see 1166 Suppl. Inf. 3). Complete transparency of annual quotas and the quantification of numbers of 1167 individual frogs per kilo must be ensured if a kilo value is to represent the number of affected 1168 individuals. It remains unclear for what reasons the calculations of the number of individuals 1169 per kilo have been reduced by seven animals as of 2018 (Tab le 2), and we remain skeptical of 1170 these numbers. 1171 Anurans involved in the international frogs’ legs trade are all r -strategists, which means that 1172 they have large numbers of offspring, a rapid development al rate, and a high reproductive 1173 output. This also makes these species more amenable to regular (monitored) harvest while 1174 remaining viable . However, r -strategists also define themselves in having highly variable 1175 population sizes over time and mortalities may be density-independent or even catastrophic 1176 (Pianka 1970). Despite relatively high individual densities of some species in agroecosystems, 1177 regular removal of thousands of individuals still raises questions about the extent that the 1178 ecosystems can compensate for this intervention . For example, negative ecological shifts may 1179 have already occurred (e.g., can ecologically more flexible species outcompete more 1180 specialised species? and how have populations of insect pests been affected by fluctuations in 1181 frog populations?). There is also no doubt that trophic interactions in certain agro -ecosystems 1182 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 such as rice fields are very complex, and we still do not have a grasp at the main drives of the 1183 complexities. For example, t ype of cultivation and human impact can have strong impacts on 1184 biodiversity. Abrupt regular removal of rice plants in a wet paddy, for instance, results in a 1185 considerable sudden loss of energy for the entire biotic community (cf. Bambaradeniya et al. 1186 2004). A decline in pond frogs (Pelophylax nigormaculatus) in rice field-dominated landscapes 1187 in Japan has been noted as a result of the modernisation of drainage systems which also led to 1188 the decline of the grey-faced buzzard (Butastur indicus ) (Fujita et al. 2015). It is clear that 1189 human impacts on nutrient supply and food web structure have strong and interdependent 1190 effects on biodiversity and ecosystem functioning, and it is therefore essential to monitor/ these 1191 both (see Worm et al. 2002). 1192 1193 These considerations may, however, be too complex to be actively explored within the 1194 framework of the EU. We highlighted that there are many internationally traded species/species 1195 groups with sales in the EU where unsustainable trade has been detected (cf. Symes et al. 2018), 1196 that could be regulated more easily. Governmental priorities within transnational cooperation 1197 projects should develop common methodological approaches that include genetics (species 1198 identification and origin) and biosecurity measures to prevent the spread of disease. 1199 But in the context of amphibians that are e.g., imported live into the EU for the exotic pet trade 1200 industry among which many are traded that are also known to be infected with Bd/Bsal, (see 1201 Wombwell et al. 2016; Nguyen et al. 2017; Fitzpatrick et al. 2018 ) even here biosecur ity 1202 measures prior to the import into the EU (incl. non -EU- European States) have not been 1203 implemented to prevent cross -infections, despite the fact that Bd was listed as a notifiable 1204 disease by the World Organization for Animal Health (O IE) in 2008 (Schloegel et al. 2010) , 1205 and Bsal in 2017 (https://www.oie.int/app/uploads/2021/03/a-bsal-disease-card.pdf, see Suppl. 1206 Inf. 3). 1207 1208 IUCN Red List assessments 1209 1210 Required data for the IUCN Red List are crucial for assessing the conservation status of species. 1211 In Red List assessments , trade in a species can either (1) be mentioned at the national/ 1212 international level, (2) go unmentioned (despite the fact that trade occurs) or, (3) if mentioned, 1213 in some cases be designated as an acute threat to a species/population . In such cases , it is 1214 particular problematic when Red List assessments are up to 18 years old (Table 3, Suppl. Inf. 1215 2, 4), and for species utilized domestically or traded internationally where overexploitation was 1216 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 already identified in 2004, but the impact on the local populations have not been well assessed 1217 (e.g., Limnonectes blythii, L. kuhlii or L. malesianus; see Table 3). 1218 1219 1220 Taxonomic uncertainties, interbreeding 1221 1222 Several Pelophylax, Limnonectes, and Fejervarya spp. are morphologically very difficult to 1223 distinguish and many taxa are taxonomically treated as cryptic species complexes (see Bickford 1224 et al. 2007) within their genera (Kurniawan et al. 2011; Dufresnes et al. 2018; Yodthong et al. 1225 2019). Therefore, challenges of quantifying actual harvest of each species are substantial if 1226 these taxa are harvested in the hundreds of thousands to millions of individuals per year . 1227 Accurate identification of species is the foundation for any management plan, and trade and 1228 conservation need to go hand in hand . Disregard of this basic knowledge and trading activity 1229 can cause fundamental damage to the species a nd, in the worst case, to respective ecosystem s 1230 (Estes et al. 2011). Unfortunately, it is precisely this taxonomic uncertainty that is exploited by 1231 companies, for example, as done in Turkey, labelling frogs as the hybrid Pelophylax esculentus 1232 which does not occur in Turkey but does in other parts of Europe (Çiçek et al. 2020). Evidence 1233 provided by genetic methods could reveal incorrect labelling in Indonesian exports of frozen 1234 frog’s legs destined for European markets with packages indicating Limnonectes [Rana] 1235 macrodon rather than as Fejervarya cancrivora , but rigorous assessments of accuracy of 1236 species identification have not been conducted (Dittrich et al. 2017; Ohler and Nicolas 2017). 1237 In 2001, Veith and colleagues could separate F. iskandari as a valid species from the F. 1238 limnocharis-complex through allozyme data. Another clear example is F. iskandari (restricted 1239 to the island of Java) which was previously traded undetected withi n the F. limnocharis-1240 complex (Kusrini 2005) and could be negatively impacted by overharvest . Apart from these 1241 examples of harvested taxa included in species-complexes with uncertainty in their taxonomic 1242 status (e.g., Holsbeek et al. 2008; McLeod 2010; McLeod et al. 2011; Dehling and Dehling 1243 2017; Yodthong et al. 2019; Stuart et al. 2020), introduction of exotic species that interbreed 1244 with closely related species or crossbreeding incidences of farm escapees into other ecosystems 1245 (Yu et al. 2015), may lead to a replacement of formerly native species (cf. Leuenberger et al. 1246 2014). In addition to these concerns is the potential for an invasive species (e.g., Lithobates 1247 catesbianus) to become a driver of ecological trophic cascades in naive ecosystems (e.g., Gobel 1248 et al. 2019) . Such issues are well known from other taxa, yet the lack of monitoring and the 1249 number of cryptic species underscores the under-appreciated risks associated with hybridization 1250 of these as yet unrecognized frog species. Species identification of skinned or frozen frogs' legs 1251 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 is impossible without genetic techniques, thus mislabeling may not have been strategic, but an 1252 indication that processors and exporters in Indonesia are not trained in frog species 1253 identification. This knowledge was not considered a prerequisite for the export of frogs’ legs, 1254 and as there are no strict checks, the trade of potentially misidentified species has been allowed 1255 to continue. More concerningly, it may also be that maintaining consistent supplies woul d not 1256 be possible if adequate scrutiny of what is in the trade, where it is from, and how availability 1257 fluctuates, are taken into account . In fact, it must be clearly emphasized that th e prerequisite, 1258 "we only use/trade what we know", has not yet been met and relevant stakeholders (including 1259 government agencies) have not made an adequate effort to address this issue. 1260 1261 1262 Ecological impact and economic uncertainties 1263 1264 Sustainable international trade can only be ensured if the use and movement of species within 1265 national borders is managed in such a way that species or populations maintain their viability 1266 and do not show shifts in physical traits due to bias in selection o f key traits (cf. Leader -1267 Williams 2002) . In fact, differences in body size in intense ly harvested populations of 1268 Lithobates [Rana] grylio are probably due to selective harvesting pressure on larger size classes 1269 (Ugarte 2004). Kusrini (2005) found that body sizes of captured adults are smaller than those 1270 of the same species in other un-harvested regions, and capturing larger adults may lead to lower 1271 recruitment rates. Similarly, the pronounced sexual dimorphism in species attractive to hunters 1272 (e.g., F. cancrivora and L. macrodon ), leads to reduction in the number of those larger 1273 individuals. According to Kusrini (2005), one important criterion for monitoring is the 1274 recording of body size. These worrying but prescient data from 17 years ago do not seem to 1275 have been properly considered until now, and viability of harvested frog populations has largely 1276 been overlooked. 1277 In this context, government s are called upon to use resources in an adapt ive and sustainable 1278 manner. Furthermore, EU commitments to Environmental impact Assessments ( EIAs) of 1279 imported wildlife mean that the EU is obligated to monitor what is in trade as well as the impact 1280 it is likely to have on source populations. As soon as the species triggers international demand 1281 and sales , importing count ries are equally held accountable to take responsibility , whereby 1282 relevant stakeholders must ensure that their consumption of exotic species does not lead to 1283 population declines. Clearly, this will entail other anthropogenically induced threats affecting 1284 these species/populations (e.g., Chen et al. 2019). It is worrying to note that there are very few 1285 studies reviewing current trade in terms of sustainability and the little information that is 1286 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 published, implies very strongly that current harvest /trade is unsustainable. For example, 1287 populations of Pelophylax caralitanus are still locally widespread in Turkey, but the species is 1288 considered endangered (Ǒz et al. 2009), not only because of habitat loss, but also because of 1289 local overexploitation for trade with the EU (Erismis 201 8; Çiçek et al. 202 1). Further, 1290 overharvest of P. shqipericus has been noted in the species’ Red List assessment ( IUCN SSC 1291 Amphibian Specialist Group 2020 h), and the unsustainable trade of this species has been 1292 highlighted (Gratwicke et al. 2010). However, populations of P. shqipericus in Albania (core 1293 distribution of the species) have not yet been considered within a conservation management 1294 plan (Eco Albania 2019). 1295 1296 Numerous examples of overexploited species assessed in the IUCN Red List assessments are 1297 detailed (see Table 3, Suppl. Inf. 2, 4) and examples of unsustainable trade at the regional level 1298 (e.g., in western Africa and that of species and species complexes in Southeast Asia) have also 1299 been presented. However, there is a severe shortage of established field studies (cf. Auliya et 1300 al. 2016; Morton et al. 2021) over longer periods of time to provide not only snapshots of single 1301 localities, populations, and their harvest status, but also long-term studies (e.g., use of pesticides 1302 and potential residues on populations in trade, impact of local population declines , if 1303 populations can maintain their role as pest control, etc.). 1304 According to Raghavendra et al. (2008) comprehensive ecological field studies in India 1305 investigating the function of anuran communities and their control of pests such as mosquitos 1306 are still in their infancy. Local knowledge in West Java (Indone sia) reveals that at least 1307 Fejervarya limnocharis is perceived in functioning as pest control (Partasasmita et al. 2016). 1308 A two-year field study in the Philippines compared prey items of the native Luzon wartfrog 1309 (Fejervarya vittigera) with that of the introduced cane toad (Rhinella marina) to determine the 1310 proportion of rice pests in their diets, and which of the two species was more efficient feeding 1311 on rice pests. It turned out that the proportion of pests eaten by F. vittigera was significantly 1312 larger than that of R. marina , which mainly preyed on beneficial arthropods in the rice-1313 ecosystems. The authors conclude that adult F. vittigera may provide effective pest control 1314 services and suggest protecting and promoting F. vittigera populations (as opposed to reducing 1315 R. marina populations) to minimize the use of insecticides (Shuman-Goodier et al. 2019). 1316 1317 1318 Is frog farming a sustainable alternative? 1319 1320 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 Due to problems of sustainability caused by the removal of species from their ecosystems (see 1321 Table 3), various authors suggest a focus on commercial frog farming (e.g., Şereflişan and 1322 Alkaya 2016; Nguyen 2017; Ribeiro et al. 2019 ). Indeed, commercialisation of frog farming 1323 appeared to be the way forward for a promising industry in many countries ( first attempts 1324 breeding Lithobates catesbeianus in the US and Canada are dated before 1900), but continuing 1325 efforts to implement these plans have proved less successful (Helfrich et al. 2009 ; Dodd and 1326 Jennings 2021). Such ventures have been discouraged since the 1930s and many problems (e.g., 1327 live food and water quality availability, risk of spreading disease, slow mass increase or growth, 1328 and economic start-up constraints) were known to the early proponents of such ventures. 1329 However, because investments are relatively low and profits can be many times higher, this 1330 branch of business creation continues. 1331 Globally, Lithobates catesbeianus is the most widespread species involved in farming 1332 operations and has been introduced for the purpose of commercial farming into more than 40 1333 countries (FAO 2021). 1334 In other parts of the world, initiatives to commercialize frog farming are also being publi cized 1335 as a result of increased demand . For example, under EU funding, the CaPFish Capture and 1336 Aquaculture programmes were launched to promote aquaculture in 10 provinces of Cambodia, 1337 primarily to promote food security in line with national government plans for fisheries 1338 development. Specifically, the Minister of Agriculture, Forestry , and Fisheries , “Veng 1339 Sakhon”, encouraged farmers to raise frogs due to an increased market demand 1340 (https://en.khmerpostasia.com/2020/10/16/frog-farming-encouraged-as-market-demand-1341 rising/, accessed, June 2022, see Suppl. Inf. 3). However, this programme is explicitly designed 1342 for national needs, not international export. 1343 Likewise in Thailand, establishment of commercial frog breeding families has been described, 1344 and limited for national consumption (Pariyanonth and Daorerk 1995). 1345 A major problem underlying establishment of commercial frog farming facilities is that there 1346 are no international standards or hygiene guidelines (see Dittrich et al. 2017). In some of EU’s 1347 major supplying countries, i.e. , Vietnam, frog farms remain being insufficiently controlled 1348 (Nguyen 2014; Nguyen and Tran 2021) implying that no health controls are imposed on farms 1349 and processing into frogs' legs, as well as testing for disease. As a result, the risk of international 1350 trade spreading diseases such as ranavirus and Bd into naive amphibian populations is ever -1351 present (cf. Gratwicke et al. 2010; Gilbert et al. 2013). However, unfavourable conditions are 1352 present, e.g., the lack of appropriate management measures, resulting in the (unintentional) 1353 release of disease-infected L. catesbeianus into the environment of suppl ier countries (cf. 1354 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 Ribeiro et al. 2019). Species escaping from breeding farms may also hybridize with congeners, 1355 and here the problem of genetic pollution needs to be addressed. 1356 An additional complicating factor for internatio nal control is that species harvested for frogs’ 1357 legs ar e exclusively non -CITES species, implying that there is no documentation across 1358 international borders. 1359 1360 1361

and Recommendations 1362 1363 The complexity of issues underlying th e frogs’ legs trade is not a priority policy item for the 1364 EU, despite several important issues reviewed herein. This strongly suggests that the EU, as the 1365 main consumer of wild harvested frogs’ legs , has deliberately shirked responsibility in 1366 addressing the many issues facing the frog’s leg trade . The important precondition for such 1367 trade must be that consumers in the EU can have a guarantee that their actions will not 1368 contribute to the decline of species they consume or cause the spread of pathogens to native 1369 species. However, to achieve this goal, all stakeholders have to work together to remove 1370 existing loopholes and implement new regulations to control the trade in the foreseeable future. 1371 Full transparency of current supply chains, including information on sourced populatio ns or 1372 commercial breeding farms, is also critically needed. Otherwise, we suggest temporarily 1373 suspending trade in certain species until such data are available and assurances made by all 1374 stakeholders. These measures result from the uncertainties highlighted here and are to ensure 1375 maintenance of viable populations in the countries of origin . Accompanying these should be 1376 awareness campaigns and education to help foster information for consumers to help them make 1377 decisions. The role of the EU should therefore be guided by the problematic conditions of this 1378 trade (unclear taxonomy, unsustainable offtakes, no disease control/biosecurity measures, 1379 reintroduction of exotic and invasive species and lack of a centrally established checkpoint for 1380 imports into the EU) in order to develop a more responsible and sustainable framework of the 1381 frogs’ legs trade . The only measure the EU has in place for non -CITES species at present is 1382 TRACES, and it generally fails to list species . In addition, t he World Trade Organization 1383 (WTO) does not require that amphibian species be clearly listed in trade, making it almost 1384 impossible to monitor. 1385 1386 One fact in particular became clear in this review : the lack of knowledge about species 1387 conservation and factors to promote implementation of sustainable harvest. The establishment 1388 of strictly supervised commercial farm ing according to industry-set protocols and hygiene 1389 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 measures, (especially in the main supplier countries), and the difficulty in implementing these, 1390 is ignored by the EU. On both sides of the trade, short-term economic benefit is more important 1391 than long-term sustainability of the trade itself. Unsustainable trade prevents continued harvest 1392 and therefor, long -term economic viability, and ult imately ecological costs will also mount 1393 unrealized until severe non-linear results accrue (e.g., crop failure due to pest outbreaks because 1394 predators are gone, as in India in the 1970s). This observation is particularly sobering because 1395 the international trade in frogs’ legs has been ongoing for decades (Le Serrec 1988; Warkentin 1396 et al. 2009; Altherr et al. 2011). 1397 It is irrefutable that the international frogs’ legs trade into the EU is riddled with uncertainties 1398 (no biosecurity measures, species identity is opaque, reported source is absent or doubtful, etc.). 1399 The EU, as the main consumer of frog’s legs , does not assume any obligation to responsibly 1400 solve problems listed in this review, but herein is challenged to address the problems identified. 1401 We can only presume that many departments and agencies within the EU are aware of the 1402 extreme complexity of this trade with its diffuse network and various databases, but clearly put 1403 economics before the conservation of natural resources or the long -term benefits and 1404 livelihoods of people involved in the trade internationally. 1405 Gratwicke et al. stated in 2010 that additional CITES listings could help reduce negative impact 1406 of international commercial trade. As stated earlier, IUCN Red List assessments of several 1407 trade-relevant anurans highlight the need for improved monitoring and creating a more 1408 regulated trade. Intensively traded species should also be re-evaluated for IUCN Red List status 1409 at more frequent time intervals in order to add up-to-date information on the conservation status 1410 of vulnerable species. More specifically, we propose that the IUCN SSC Amphibian Specialist 1411 Group designate a new working group that monitors and evaluates the conservation/threat status 1412 of particularly intensively harvested/traded species involved in the frogs’ legs trade at regular 1413 annual intervals. This information is critical to be implemented into CITES for timely decisions. 1414 The increasing incidence of infectious diseases (both within a species as well as zoonotic 1415 spillovers) via the wildlife trade correlates closely with the loss of biodiversity in source 1416 countries and is considered a worrying environmental problem that must be counteracted as a 1417 matter of urgency (see Kiesecker 2011). 1418 1419 More science required 1420 1421 Modern innovative scientific methods are required to ensure a fully transparent, legal, traceable, 1422 and sustainable trade. We will need to i mplement scientific methodologies to distinguish 1423 farmed vs. wild individuals (cf. Dittrich et al., 2017) and to obtain sufficient data on all source 1424 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 populations to ensure that harvest levels fall below annual population replacement levels . 1425 Basically, taxonomic uncertainties need to be clarified and the formation of specific research 1426 groups (e.g., taxonomists, field ecologists, experts of current legal framework s, etc.) is highly 1427 recommended. 1428 1429 To prevent the spread of infectious diseases , biosecurity measures need to be established at 1430 distinct points along the trade chain. Interestingly, such measures were already proposed at the 1431 37th Standing Committee of the Convention on the Conservation of European Wildlife and 1432 Natural Habitats, in December 2017 ( https://rm.coe.int/recommendation-on-biosafety-1433 measures-for-the-prevention-of-the-spread-/168075a4b0, accessed May 2022 , see Suppl. Inf. 1434 3), but never implemented. Therein, recommendation No. 197 refers to “biosafety measures for 1435 the prevention of the spread of amphibian and reptile species diseases”. This document lists 10 1436 recommendations for contracting parties, none of which include information on species traded 1437 either alive or processed for the frogs’ legs trade. The majority of recommendations encourage 1438 support for increased research. However, recommendation 5, “Using the most appropriate legal 1439 framework, and at the earliest opportunity implement immediate restrictions on the amphibian 1440 and reptile species trade whe n an emerging pathogen spread with significant impact on wild 1441 populations has been identified until necessary preventive and management measures are 1442 designed, based on evidence, throughout the entire commercial chain ”, does not reflect an 1443 expansion of the regulatory framework but describes a direct suspension of trade in an infected 1444 species. With regard to the prevention and spread of known diseases identified by OIE (such as 1445 Bd), we reference a document from 2015 by the Standing Committee to the Convention on the 1446 Conservation of European Wildlife and Natural Habitats on the Recommendation on the 1447 Prevention and Control of the Bsal fungus (https://rm.coe.int/1680746acf, accessed May 2022, 1448 see Suppl. Inf. 3). The implementation of these recommendations, however, cannot be verified. 1449 The need for supervision of hygiene and veterinary inspections for edible frogs (also those 1450 farmed and are non-native) in the Asian region has been indicated (Grano 2020; Borzée et al. 1451 2021), given the tight link s observed between market locations and detection of Bd in wild 1452 amphibian populations. 1453 Hardouin (1997) indicated that authorities in countries that import frogs' legs should be 1454 encouraged to regulate international trade more close ly by banning products that cannot be 1455 sourced from farms where they are subject to official controls. He further notes that Europe 1456 cannot ignore risk of wild harvests that may lead to declines in local frog populations as a result 1457 of overexploitation. We also recommend the listing of some if not all species in trade on CITES 1458 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 App. II. International trade should be regulated for those species that are already documented 1459 in an IUCN Red List threat category and those for which there is published evidence that trade 1460 has depleted local or regional populations. Taxa in species complexes whose morphological 1461 differentiation is not readily possible or are processed only as frogs’ legs are particularly 1462 vulnerable, so standardised use of molecular approaches to verify and monitor trade would be 1463 particularly useful. 1464 1465

outlined in this review provide strong clear recommendations for both source and 1466 consuming countries. Promptly counteracting abuses in the international trade of frogs' legs by 1467 adapting existing legislation and applying the precautionary principle to prevent irreversible 1468 damage to populations or species will help to promote the sustainability of the trade in the long-1469 term. Recommendations for source and consuming countries are listed separately below. 1470 1471 We recommend that source countries should: 1472 • conduct field surveys at comparative study areas to estimate size and trends of wild frog 1473 populations and of the impact of harvest for both national consumption and international 1474 trade. 1475 • validate species identity through centralised authorities to check and certify trade 1476 exports through the use of genetic tools 1477 • include analyses of trade data and standardize documentation of volumes ( number of 1478 individuals must be considered, not an estimate of the number of individuals by means 1479 of weight). 1480 • establish long-term field studies in selected areas (where regular harvest takes place) to 1481 assess biotic communities in relation to the application of pesticides. 1482 • make non-detriment findings (NDFs) a result of CITES listings at regular time intervals 1483 • examine the domestic/national use of frogs’ legs versus exports to decipher the 1484 complexity of this resource use and improve equity and fairness within each source 1485 country. 1486 • study mortality rates of frogs in transport and processing prior to export. When 1487 identifiable loopholes exist, source countries should make every effort to minimize 1488 mortality and economic loss. 1489 • accurately and regularly verify harvest rates, including both local as well as harvest for 1490 international trade. As highlighted earlier, it has been estimated that offtakes of edible 1491 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 frogs on a national level can be seven times as much as that of annual exports (Kusrini 1492 2005). 1493 • establish conservative but reasonable harvest and export quotas based on high quality 1494 data for targeted species/populations and taking into account other threats that affect 1495 species/populations. 1496 • ban harvest during the mating season. Specific management measures have been 1497 highlighted for the harvest of Pelophylax spp. in Turkey and claim, “that further harvest 1498 restrictions are essential for the sustainability of Anatolian water frog populations” 1499 (Çicek et al. 2020). 1500 • evaluate and implement adaptive management measures for all harvested species, i.e., 1501 the ban of certain size classes for a given period/season as a default to help insure 1502 sustainability. 1503 • define and implement stricter regulations for farming operations to ensure closed 1504 systems, prevent re -stocking from the wild , release of farmed animals back into the 1505 environment, as well as avoid farming of non-native species when possible. 1506 • register and monitor all export companies and their suppliers, and require that exporters 1507 identify processed frog products by DNA analysis. 1508 1509 Consumer countries have the obligation to take appropriate responsibility for the consumption 1510 of a resource. Accordingly, it would be obligatory to transparently inform relevant societies on 1511 which information basis trade is permitted. 1512 1513 We recommend that consumer countries should: 1514 • implement a centralized database to document all imports of all wildlife and list 1515 species and quantities in the Annexes of the EU Wildlife Trade Regulation, using the 1516 LEMIS database as a model. 1517 • list all species in trade in CITES to regulate international trade and enforce 1518 restrictions. 1519 • implement NDF's for the import of species from the wild, regardless of CITES status. 1520 • provide captive breeding guarantees for species claimed to be of captive origin. 1521 • push for improved standards (based on revised guidelines), such as import bans on 1522 wild harvested species that have been evaluated in one of the IUCN Red List threat 1523 categories. 1524 • impose trade suspensions if trade data are not provided in full transparency. 1525 Author-formatted, not peer-reviewed document posted on 01/09/2022. DOI:  https://doi.org/10.3897/arphapreprints.e94243 • check all imports for pesticides and other pollutant residues. 1526 • assist range states in conducting surveys of wild frog populations and to create a 1527 biobank with references samples from species/populations of major harvest regions to 1528 cross-check genetic identities of shipments imported. 1529 • conduct random DNA analysis of frogs’ legs shipments to determine if shipment 1530 labelling is correct and ban imports for persistent mislabelling. 1531 • allow only positively identified, skinned, processed, and frozen frogs’ legs to be 1532 imported to avoid the introduction and spreading of diseases and invasive species. 1533 • rigorously catalogue all imported species with standards parallel to those implemented 1534 under LEMIS. 1535 • improve regional monitoring schemes with joint-efforts between stakeholders and 1536 governments to bolster the sustainability of the trade along multiple facets. 1537 1538

1539 1540 We wish to thank Chris Shepherd and Jordi Janssen for providing data and Andrea Höppner for 1541 her technical assistance in visualising trade routes . We also have a number of anonymous 1542 people we want to thank for being responsible for data sources of data from private companies 1543 to countries and their respective a gencies involved in the trade. This review was financially 1544 supported by the German foundation “Stiftung Zukunft Jetzt!” 1545 1546 1547 1548 1549 1550

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