Unsustainable harvest of water frogs 369


FIG. 3 Total harvest, total of harvest exported, total harvest in the Seyhan and Ceyhan Deltas, and the total export value during 2000–2017 (TÜİK Fisheries Statistics, 2018).


There are few demographic models of amphibian popu-


lations because of lack of data to estimate many model para- meters including, in our study, information on harvest rates across the landscape, demographic rates from unharvested populations, emigration and immigration rates, and direct estimates of annual fecundity. In addition, the short dur- ation and restricted spatial scale of our study decreases the reliability of model results. Nevertheless, the drastic declines projected for harvested populations suggest that the current harvest rates are unsustainable. Long-term mark–recapture and monitoring over larger areas would provide better data for estimating model parameters. Large-scale collections of frogs from the wild not only re-


duce population sizes (Schlaepfer et al., 2005;Altherr et al., 2011), but also disturb habitats (Goode et al., 2004), introduce exotic pests and parasites (Franke & Telecky, 2001), spread diseases to native fauna (Daszak et al., 1999), and reduce eco- logical control of mosquito populations (Raghavendra et al., 2008;Mohneke, 2011) and agricultural pests (Abdulali, 1985; Kusrini, 2005). Thus, addressing the impacts of overharvesting is a priority for conservation (Gilbert et al., 2012). Another concern is that exported live frogsmaybe sold in


pet shops in countries outside the species’ native range, and could in some cases become invasive species. Anatolian frogs have already entered Europe via commercial trade, and are expected to invade Western and Central Europe further, with risks of large-scale hybridization and intro- gression (Holsbeek et al., 2008). Annual global frog con- sumption is 0.8–3.2 billion individuals (Gratwicke et al., 2010), and its effects show a particular spatio-temporal pattern. As a country’s frog populations decline as a result of overharvesting, harvest bans shift the pressure to other countries. After frog harvesting was banned in France and Romania, exports of wild-caught frogs from India and Bangladesh increased, leading to population declines and subsequent harvest bans in these countries (Török, 1999; Kriger & Hero, 2009; Altherr et al., 2011). This caused the


harvest pressure to shift once again, this time to Indonesia and China, which are now experiencing this extinction domino effect (Altherr et al., 2011), with many frog species at risk of extirpation and extinction (Carpenter et al., 2007; Warkentin et al., 2008; Chan et al., 2014). Our study provides insights into the position of Turkey


in this extinction domino line. Frogs in Turkey are harvested almost exclusively from the wild, and the country provides c. 4% of Europe’s frog imports (Altherr et al., 2011). Typical incomes from frog harvesting are low, but a main source of income for most of the harvesters. Economic dependence on the harvest increases the pressure on frog populations, and the ecosystems of which they are a part. Unsustainable and unregulated harvest also increases economic inequalities. The results of our simulations show that the extremely high rates of harvest will result in the extirpation of these frog populations and thus remove the harvesters’ livelihoods. A challenge for the regulation of the frog harvest in


Turkey is taxonomic uncertainty. The genus Pelophylax (Rana) is a poorly identified species complex comprising genetic, phylogenetic and ecological forms (Plötner, 2005; Akın et al., 2010; Plötner et al., 2010). Genetic analyses show there could be cryptic species in Anatolia with similar morphology (Akın et al., 2010). Systematical uncertainty, lack of knowledge of the distribution of genetic lineages, and the morphological similarity of Anatolian water frogs (Plötner & Ohst, 2001;Akın et al., 2010; Plötner et al., 2010) hinder species identification through morphology. The frog-exporting companies turn this incognizance into an opportunity, labelling all frogs as Pelophylax esculentus, a hybrid form known as ‘edible frog’, which is native to Europe but absent in Turkey. In addition to the need for clarification of the systematics of Anatolian water frogs using genetic methods, genetic identification is required for certification during export. Export data for the Seyhan and Ceyhan Deltas were obtained from frog processing companies, which receive


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


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