Unsustainable harvest of water frogs 365


in two frog species resulted in the recovery of the over- exploited populations (Altherr et al., 2011). Turkey is an important source country the for frog trade.


Although there is no domestic consumption except in some restaurants catering for tourists, harvesting of wild frogs to satisfy international demand is expanding. Anatolian water frogs (Pelophylax spp.) form a species complex comprising at least two, and possibly up to five, closely related species (Akın et al., 2010; Plötner et al., 2010). These species have been harvested for .40 years (Akın& Bilgin, 2010; Kürüm, 2015): Turkey exports nearly 700 t of frogs annually, a trade that is worth nearly USD 4 million (Kürüm, 2015). During 1999–2009 Turkey was the third leading frog leg supplier to the European Union, with 4%, after Indonesia (84%) and Viet Nam (8%) (Altherr et al., 2011). Despite the threatened status of amphibians worldwide,


and the importance of wildlife trade as a threat to species, few studies have quantified the impact of trade on the via- bility of amphibian populations. In addition, there are no population-level studies of the frog harvest in Turkey des- pite the country’s importance in this trade. Here we assess the current population status of Eastern Mediterranean Anatolian water frogs (Pelophylax spp.), which are heavily harvested in the Seyhan and Ceyhan Deltas in Adana prov- ince. We (1) analyse the dynamics of a harvested frog pop- ulation, (2) quantify the impact of harvest on the viability of the frog population, (3) make projections of frog harvest and viability under different future harvest regimes, and (4) make recommendations for conservation of Anatolian water frogs and for the future of the frog trade. Our assess- ment highlights the need for reconsideration of national conservation measures and certification of animals har- vested from the wild that enter the international market.


Methods


Surveys Initially,we surveyed Seyhan and Ceyhan Deltas in southern Turkey to determine the current status and harvest of frogs.We interviewed harvesters and exporter companyman- agers, and selected survey locations in areas where the spe- cies was being harvested regularly (harvesters collect frogs from natural habitats, intermediaries organize the harvest- ers according to the demands of exporters, and exporting companies process the frogs). We then conducted field surveys during February–April (spring), June–August (sum- mer) and October–November (autumn) in 2013, 2014 and 2015.We surveyed in a total of 10 locations in three macro- habitats: five ponds, three irrigation canals and two streams. Sampling was by four surveyors, who captured frogs during night-time by hand or with a fishing net (the methods used by harvesters).We determined the sex of


We developed a stochastic, density-dependent,matrixmodel with two stages, juvenile and adult, and a time step of 1 year. We set the age of first reproduction at 2 years, and parame- terized the matrix model according to post-reproductive census:


0 F ×Sa Sj Sa


where Sa and Sj are annual survival probabilities of adults and juveniles, respectively, and F is annual fecundity of adults (number of daughters per female per year). Thus, the element of the matrix representing reproduction (F × Sa) incorporates survival of adults from the census in the previous year to breeding. Lacking a direct estimate of F, we calculated the product F × Sa as the number of fe-


male juveniles in year t per adult female alive in year t−1 (Table 1). The sex of juveniles cannot be determined, so we assumed 50% females at birth. Survival rates Sj and Sa


Oryx, 2021, 55(3), 364–372 © The Author(s), 2020. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605319000176


each individual by secondary sexual characteristics, mea- sured snouth-vent length with a caliper to the nearest 0.01 mm, used a digital scale to record weight to the near- est 0.1 g, applied a mark with a visible implant elastomer (Northwest Marine Technology, Inc., Shaw Island, USA; Çiçek, 2009; Çiçek et al., 2011), and then released each individual at its point of capture within 30–40 minutes. Before marking, we applied a local anaesthetic (ethyl chlor- ide) to the body surface of the implant and after marking we applied a broad spectrum pomade (a mix of Furacin, Bacturaban and Stafine pomade) to prevent infection. Ethyl chloride is widely used, in the form of a topical anaesthetic spray, to decrease pain fromneedle puncture during injection procedures (Polishchuk et al., 2012), and produces instant skin anaesthesia (Armstrong et al., 1990).


Demography


We surveyed four times in each of the three seasons in all 3 years, giving 36 samples in each of the 10 locations. During each survey we recorded previously captured, marked and released individuals, and we marked and re- leased all other individuals. We created capture histories for all individuals to estimate population parameters using MARK 8 (White & Burnham, 1999; Cooch & White, 2017) and estimated population size (assuming a closed popu- lation within a season) using model h (heterogeneity) in CAPTURE (Otis et al., 1978; White et al., 1982). We cal- culated apparent annual survival rates (f) using the Cormack–Jolly–Seber model (Cormack, 1964; Jolly, 1965; Seber, 1965), and used Akaike’s information criterion for model selection.


Population viability analyses


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