The global amphibian trade

Amphibians show global declines as a result of multiple interacting drivers including pollution, invasive species, habitat loss and fragmentation, diseases and overharvesting for human consumption and the pet trade (e.g., Hedges 1993; Collins and Storfer 2003; Stuart et al. 2004; Andreone et al. 2006; Pounds et al. 2006; Collins and Crump 2009; Gratwicke et al. 2009; Rödder et al. 2013; Herrel and van der Meijden 2014; Martel et al. 2014).

International trade has also introduced new amphibian pathogens and spread them along trade routes (Fisher and Garner 2007; Jenkins 2013; Martel et al. 2014) and exacerbated many species’ risk of extinction (Stuart et al. 2004; Fisher and Garner 2007; Bishop et al. 2012; Jenkins 2013). This heightened risk demonstrates the need to understand how species are moved within and between countries and continents. At the same time, there is an immediate need to identify, from a European perspective, loopholes and deficiencies in the trade with respect to strengthening current biosecurity legislation and (stronger) implementation of existing wildlife laws at national and international scales.

Amphibians are traded nationally and internationally for many purposes and needs. Species within the family Ranidae and the genera Ambystoma, Bufo, Notophthalmus and Xenopus are commonly used for biomedical and educational research (Alworth and Harvey 2007; O’Rourke 2007). The international frog leg industry relies on fewer than ten species that are of significant economic value (Veith et al. 2000; Schlaepfer et al. 2005; Altherr et al. 2011), but many thousands of tons are produced and shipped globally (e.g., Jensen and Camp 2003; Warkentin et al. 2009). In some regions amphibians are also harvested in very large numbers for local consumption (Mohneke et al. 2010; Neang 2010). Cox et al. (2008) mention 212 species affected by overexploitation (Picco and Collins 2008). The IUCN Red List (2015) records 317 species that are regularly hunted and trapped. Of these, more than 290 are targeted for the international pet trade and consumption purposes (IUCN Red List 2015). Species from South and Central America and Madagascar are predominantly collected for the pet trade (noting that the consumption trade in several species in South America is also substantial; see Catenazzi et al. 2010; Altherr et al. 2011) whereas most species in East and Southeast Asia and West Africa are utilized for consumption and medicinal purposes on a local scale and/or are internationally traded for food (Stuart et al. 2008; IUCN Red List 2015). The commercial trade in amphibians demonstrates that species and populations are directly and indirectly impacted; direct impacts specifically target unsustainable and illegal trade and suggest local and regional overexploitation (e.g., certain Mantella spp. detrimentally impacted by the pet trade; Andreone et al. 2005), whereas indirect impacts indicate that species and products thereof crossing borders carry infections, and consequently can contribute to disease outbreaks in captive and wild amphibian populations (Cunningham et al. 2015). Because of the severity of recent trade-related amphibian pathogen outbreaks in the EU (see Spitzen-van der Sluijs et al. 2013), we focus on the policies and capacity of the EU in finding sustainable solutions. In this paper we highlight issues that urgently need a rigorous control of the global amphibian trade under the premise that trade activities should not put the survival of amphibian species further at risk.

Indirect trade effects—infectious amphibian diseases transmitted through trade

Worldwide trade in wildlife has increased the potential for translocation of diseases, and poses risks to human, crop, livestock and wildlife health (Karesh et al. 2005; Marano et al. 2007). The chytrid fungus, Batrachochytrium dendrobatidis (Bd), has led to significant declines in amphibians (Daszak et al. 2003; Alroy 2015), and is widespread in more than 50 countries across four continents with more than 520 species known to be Bd-infected (Olson et al. 2013; Global Bd-Mapping Project 2015). Since its discovery in the late 1990s, detrimental impact of the fungus on susceptible amphibian species and populations has been highlighted in hundreds of scientific publications, but standardized practical solutions still need to be implemented on an international scale (see Pessier and Mendelson 2010) and meanwhile the disease remains a formidable threat to populations of anurans (Woodhams et al. 2011; Scheele et al. 2014).

While the origin of Bd remains unclear (Farrer et al. 2011; Rosenblum et al. 2013), several studies have linked its spread to global amphibian commercial trade (Fisher and Garner 2007; Garner et al. 2009; Schloegel et al. 2009; Peel et al. 2012). A most worrisome issue is the potential for the generation and spread of more virulent or infectious recombinant genotypes of pathogens when previously isolated lineages come into contact through amphibian trade and this is particularly true for Bd (Farrer et al. 2011; Schloegel et al. 2012).

Other amphibian pathogens that have caused mass mortality in amphibians, such as ranavirus, are known to spread through amphibian pet and bait trades, sometimes even across continents (Pasmans et al. 2008; Picco and Collins 2008; Kolby et al. 2014). A new fungus, Batrachochytrium salamandrivorans (Bsal), was recently isolated in western European salamanders of the genus Salamandra (Martel et al. 2013); the pathogen is suspected to have entered the continent through trade in Asian salamanders and has caused severe disease outbreaks in salamanders in the Netherlands and Belgium (Martel et al. 2014). In the Netherlands, within 7 years after the supposed introduction of the fungus, a Salamandra salamandra population declined by 99.9 % (Spitzen-van der Sluijs et al. 2016). Lately Bsal has also been detected in S. salamandra in Germany in both wild and captive salamanders and likewise in captive salamanders in the United Kingdom (Cunningham et al. 2015; Sabino-Pinto et al. 2015; Spitzen-van der Sluijs et al. 2016). The Scientific Working Group of the European Union recently (June 2016) decided that an import stop for Asian salamanders should be implemented by placing those salamanders on Annex B of the EU regulation 338/97, but due to administrative problems (and not realizing the urgency to stop this threat), this decision probably will only become effective in 2017 (UNEP-WCMC 2016).

Commercial trade of poison arrow frogs (Dendrobatidae), reported by Gorzula (1996), Pepper et al. (2007) and Brown et al. (2011), spreads infection as Bd-infected species are imported from Central and South America into Western Europe via the pet trade. Dendrobatidae spp. reported by all importing countries compared to those reported by EU member States initially show an increasing trend over the last decade, and despite a slight drop of imports from 2012 onward (Fig. 1), a significant risk of introducing infectious pathogens remains because biosecurity measures at the EU level have not been implemented.

Fig. 1
figure 1

Source UNEP-WCMC trade database (2014)

Import numbers of Dendrobatidae spp. reported by importing countries globally and the European Union. Values of 2014 and 2015 respectively, still remain incomplete in the documentation process.

Full size image

Cross-infection between Dendrobatidae spp. with other amphibian species, including salamanders, has not been ascertained; however, the presence of the chytrid fungus among pet species has been documented (Pasmans et al. 2004; Spitzen-van der Sluijs et al. 2011). Dendrobatidae spp. have regularly been identified as Bd-positive among tested captive individuals (reported by Mutschmann in litt. to Auliya, March 19, 2013; for species, see Table 1). Although it is not possible to ascertain exact time and location of infection, cross-infection through other captive species cannot be ruled out. A field study in French Guiana recorded Bd-positive specimens with low levels of infection in two wild populations of Dendrobates tinctorius (Courtois et al. 2012). Bd-positive specimens of the same species were detected in an ex situ breeding program containing confiscated animals in São Paulo State, Brazil (De Paula et al. 2012). These reported issues are considered important as D. tinctorius triggers high international demand (see Table 1). Individuals of most dendrobatids that tested Bd-positive in Germany (Table 1), originated from the species range states.

Table 1 Bd-positive Dendrobatidae spp. held in captivity in Germany.
Full size table

Several widely traded amphibian species are vectors for a range of different pathogens. The North American Bullfrog (Lithobates catesbeiana) may introduce ranavirus, which can be found even in frozen frog tissues (Duffus 2009) and Xenopus laevis may carry Bd (Weldon et al. 2004; Vredenburg et al. 2013). Mycobacteria have been demonstrated in recently imported Western Clawed Frogs (Xenopus tropicalis) and East Asian Bullfrogs (Hoplobatrachus rugulosus) intended for trade (Suykerbuyk et al. 2007; Gilbert et al. 2013).

Direct trade effects—consumption and pet trade

Large quantities of frog legs are imported annually into the EU; however, the estimates vary among studies. According to Jensen and Camp (2003) and Altherr et al. (2011), 4600 tons of frog legs were imported annually between 2000 and 2009. Eighty-four percent of which were probably caught in the wild and supplied through Indonesia (Kusrini and Alford 2006); with one kilogram of frog legs representing around 20–50 individuals. Warkentin et al. (2009) reported that 90–230 million individual frogs are destined for European frog leg trade on an annual basis. In addition to frog legs, live and frozen whole frogs are also imported (Mazzoni et al. 2003; Gratwicke et al. 2009). High volume trade can have serious detrimental impacts on amphibian species (see Cox et al. 2008).

The international pet trade causes severe pressure on amphibian diversity, especially on restricted range species (Young et al. 2000; Pasmans et al. 2004; Andreone et al. 2008; Smith et al. 2009). The Global Amphibian Assessment (GAA) (Chanson et al. 2008) identified 47 amphibian species predominantly threatened by unsustainable collection for the international pet trade (Hoffmann et al. 2008; also see Crandall 2009). Among these species, 27 are not listed on the appendices of CITES e.g., Scaphiophryne boribory and Lyciasalamandra spp.; seven of these species are assessed as threatened according to the IUCN Red List criteria (IUCN Red List 2016), and six of these seven species are overexploited for scientific purposes, e.g., L. billae (Kaska et al. 2009). Several cases of illegal activities have been reported (e.g., Holden 1998; Pistoni and Toledo 2010; De Paula et al. 2012), including collection within nature reserves (Wang et al. 2004) and laundering of wild-caught animals as captive-bred (Nijman and Shepherd 2010). For example, in 2004-05 Thailand imported 1290 live “captive-bred” Dendrobates spp. from Lebanon, with claimed origins in Kazakhstan (UNEP-WCMC trade database 2014), but officially registered captive breeding facilities in these countries could not be verified (Nijman and Shepherd 2010).

The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) regulates international trade via a controlled licensing system and regulations on quotas for harvest.

Of the more than 7400 amphibian species recognized by the scientific community (Frost 2015), 208 species (2.8 %) are currently listed in the three appendices of the convention (CITES Species Checklist 2015). The European Union (EU) Wildlife Trade Regulation implements the provisions of CITES (EU Commission Regulation 2014), which includes additional requirements, and adds a further appendix (Annex D) that monitors the import of non-CITES listed species (European Commission 2010). Annex D lists 46 species bringing the total of all species listed in Annexes A–D to 256 (3.4 % of all amphibian species)—the three Annexes A–C largely correspond with the CITES Appendices I–III; (see Table 2). Thus, international trade is monitored in only a tiny fraction of amphibian species. Despite the fact that more than almost 98 % of all amphibians can be freely shipped across borders, various trade issues are also distinct among CITES species, of which the most important ones are highlighted below.

Table 2 Number of amphibian species listed in Appendices of CITES and on Annexes of the EU Wildlife Trade Regulations according to Frost (2015; accessed: July 13, 2015)
Full size table

Most wanted—poison arrow frogs

Poison arrow frogs (family Dendrobatidae) represent one of the most sought-after group in the international pet trade (Lötters et al. 2007). From 2000 to 2014, more than 180,000 Dendrobatidae spp. (“live”, “specimens”, “bodies” and “eggs”; see UNEP-WCMC trade data, http://trade.cites.org/—accessed, April 25, 2016) were reported as legally traded by exporting countries on a global scale, but many steps within the trade chain are poorly documented, e.g., mortality rates from the point of harvest to the exporter and transport mortalities from the exporter to import destinations (but see Brown et al. 2011; Ashley et al. 2014; Wombwell 2014).

Our analysis of UNEP-WCMC trade data of imports into the EU during 2000–2014, indicates dendrobatid imports into the EU from countries where these animals naturally occur but also from countries beyond their natural distribution range. Because of its illegal nature, no estimate of the number of individuals traded can be given. Due to lax regulations and implementation, trade in illegally imported specimens in Europe is made very easy through the use and uncritical acceptance of the category “captive bred” for many of them. From rare (published) confiscations it is clear that illegal shipments may contain hundreds of specimens (Pistoni and Toledo 2010, report a confiscation of 560 dendrobatids). During one action in Brazil several hundred dead specimens that were destined for illegal export were uncovered. Therefore, based on this example, known illegal exports could easily account for a volume with a size of ca. 10 % of the legal trade, and thus increase the pressure on wild populations even more. The top five dendrobatid-exporting countries were, in increasing order of trade volume, Guyana, Costa Rica, Peru, Suriname, and Panama. Panama and Suriname were highlighted as major exporters of species occurring within their borders, with the former documenting 33,280 and the latter 6199 specimens of poison frogs exported to the EU. Canada tops the list of non-range states (66 %) exporting dendrobatids into Europe, with 11,077 exported specimens, of which 98 % were claimed as captive-bred. The main European importing countries (in increasing order of trade volume) are Spain, Switzerland, Netherlands, Belgium and Germany. Germany imported 28 % of 54,097 specimens, and its leading role in the trade of live amphibians and reptiles has been highlighted earlier (Auliya 2003; Engler and Parry-Jones 2007).

Two species of dendrobatid frogs (CITES Appendix II) from northern South America merit special attention because of known ongoing illegal trade (e.g., Pistoni and Toledo 2010): Dendrobates tinctorius, a species occurring in the Guianas and northern Brazil, and Adelphobates galactonotus, a species endemic to the southeastern Amazon basin in Brazil. Both occur in isolated populations, with high variation in color pattern among them (Lötters et al. 2007; Hoogmoed and Avila-Pires 2012).

Brazil prohibits the export of all native fauna and flora. It has never issued any export permit for D. tinctorius (UNEP-WCMC trade database 2014), and only a few export permits for A. galactonotus covering 27 specimens for scientific purposes issued between 1993 and 1997. Given this lack of export permits, live A. galactonotus should not be found outside Brazil, but twelve specimens were illegally imported into Germany, in 1996 (Pieper and Pieper 1997). These specimens are very likely the founding stock for most captive specimens; trade in captive-bred specimens flourished, in spite of alerts to CITES authorities in several European countries and the CITES Secretariat. Adelphobates galactonotus were regularly traded as captive-bred, although a newly discovered colour morph from Brazil (at least 40 specimens) with restricted distribution surfaced in Germany in 2013, only weeks after it had been officially described in a scientific publication, fetching prices of € 350–700 ($400–800 USD) per specimen (pers. comm., M. Hoogmoed). The continued presence of a large, mainly captive-bred population in Germany, enabled continued illegal imports of this species, with wild-caught smuggled animals entering the market disguised as captive-bred.

As to D. tinctorius, Guyana and Suriname allow legal export of this species under a voluntary yearly quota, whereas Brazil and French Guiana prohibit exports. This situation permits laundering of Brazilian specimens under the quota of exporting countries due to poor border control among countries. An illegal export from Brazil was prevented when a shipment of 281 D. tinctorius and 279 A. galactonotus, destined for Germany, was confiscated in 1999 at the airport in São Paulo (Pistoni and Toledo 2010)—as with A. galactonotus, different populations of D. tinctorius have unusual colour patterns that allow to identify the origin of individuals. In 2000, the CITES Animal’s Committee requested Suriname to provide details about the sustainability of its D. tinctorius trade, and in 2001 the CITES Standing Committee suspended imports until this information was provided (https://cites.org/sites/default/files/eng/com/ac/17/E17i-04.pdf—accessed April 23, 2016). However, the ban was lifted in 2008 even though Suriname never provided the requested data, and the country continues to export this species under the same quota it has maintained since 1995.

Insufficient legislation, implementation, harmonization, and policy

Poor international trade regulation and monitoring enables exploitation and threatens many amphibian species. Commercial trade of around 98 % of the world’s amphibian (non-CITES) species is currently not regulated. The first and principal problem is that the World Customs Organisation (WCO) lacks a unique identifier (code) for amphibians in its harmonized system (http://www.wcoomd.org/en/topics/nomenclature/overview/what-is-the-harmonized-system.aspx—accessed July 13, 2016). Without a unique identifier that allows all parties to be aware that a shipment contains amphibians, it will continue to be difficult to trace flow of the European amphibian trade, and thus virtually impossible to implement measures, e.g., compliance with international standards related to transport, disease control, hygiene, or quarantine measures.

As a result, amphibians are either lumped in the category “other” or are categorized as tropical fish (Gerson et al. 2008). This deficiency makes it almost impossible to document any trade in species or numbers imported into the EU. Even though trade in CITES-listed species is regulated through permits from exporting and importing countries, listed species can be smuggled across international borders to take advantage of legal export markets (e.g., Pepper et al. 2007; Pistoni and Toledo 2010; Nijman and Shepherd 2011; De Paula et al. 2012). The import/export permit system does little to monitor or prevent international transport mortalities or along the trade chain prior to export—a conservation and animal welfare concern which is largely neglected (Brown et al. 2011). While population monitoring is supposed to occur for CITES-listed species to assure sustainable harvest, monitoring of natural populations and surveillance of domestic trade and consumption to prevent overharvest is widely lacking (Warkentin et al. 2009).

It is obviously difficult to quantify a market that is small by international standards in terms of both tonnage and money. However, this trade is enormous in terms of individuals (see above for frog legs); it has the potential to have serious detrimental impact on some species, and carries the risk of spreading pathogens and transmitting infectious diseases with very large impacts on amphibian biodiversity (Catenazzi et al. 2010).

The current global distribution of Bd has not been explicitly recognized by the World Organisation of Animal Health (OIE). Ongoing global expansion of Bd and its potential detrimental impact on local species and populations is an essential information source that needs to be taken into account by OIE to bring standards up to date; e.g., biosecurity measures along trade routes. Although the OIE rapidly updates standards (Bd and Ranavirus were included as notifiable amphibian diseases in 2008; see OIE Aquatic Animal Health Code 2011), no further updates have been made in the context of mitigating and controlling their spread or to establish sanitary safety of internationally traded amphibians (Schloegel et al. 2010). The very recent agreement between OIE and CITES to collaborate on global animal health issues is an important step forward, but in order to truly fulfill the goal of protecting CITES-listed species and biodiversity, this joint-venture also needs to consider wildlife diseases (see CITES and OIE Initiative 2015, accessed, April 10, 2016). Recently, the Standing Committee of the Bern Convention adopted a recommendation on prevention and control of Bsal that calls for “appropriate science-based pre-import risk screening for infectious diseases of live animals in animal trade” and “impose immediate restrictions on salamander and newt trade while a scientific risk assessment is being developed and until necessary measures are designed, as a preventive measure against the introduction of Bsal through pet trade” (Bern Convention 2015). Trade restrictions are consistent with the widely implemented precautionary approach and will help prevent the introduction of pathogens such as Bsal (UNEP-WCMC 2016).

The combination of overexploitation and spread of diseases can result in the loss of amphibians from some habitats and can affect the functioning of ecosystems and the services they provide. Disappearance of amphibians is predicted to have cascading effects both in terrestrial and aquatic food-webs given the central positions they occupy in those webs, both as tadpoles and as adults. For example, at Hubbard Brook in New Hampshire the biomass of salamanders easily outweighs the combined biomass of birds and mammals and they have a substantial effect on the forest-floor part of the ecosystem (summarized by Hairston 1987). Moreover, they are indicators of the healthiness of terrestrial biomes owing to their sensitivity to environmental changes (Stebbins and Cohen 1995). The enormous ecological value that amphibians contribute to e.g., neotropical ecosystems has been recently outlined by Cortéz-Gómez et al. (2015). Because in many species tadpoles and adults occupy different (ecological) niches, it is said that “the loss of a single amphibian species is akin to losing two species” (Whiles et al. 2006; Mendelson 2011; Whiles et al. 2013).

Issues related to the global conservation of amphibian species are manifold and urgently need to be addressed (Bishop et al. 2012), including the major challenge to prevent introduction of infected disease vector species into naïve amphibian populations (Cunningham et al. 2003; UNEP-WCMC 2016).

Conclusions and recommendations

Current trade regulations need to be vastly improved and rigorously enforced to ensure protection of threatened species and to allow a responsible and sustainable global amphibian trade. In this context, we suggest the following measures to improve capacity of monitoring and regulating amphibian trade:

  1. 1.

    Recommend to the World Customs Organization (WCO) that its Harmonized System (HS) be amended to specifically include codes for live amphibians and amphibian meat and encouraging member administrations to make provisions for amphibians in their domestic tariffs. The resolution “Further steps to combat the amphibian crisis” that was passed at the IUCN’s 5th World Conservation Congress (WCC-2012-Res-020) already contains a suggestion in this direction, but we are unaware of any progress towards harmonization. WCO partners such as CITES, the EU and the European Free Trade Association (EFTA), UNEP, UNESCO, and many others should raise awareness within the WCO of this need to update the Harmonized System.

  2. 2.

    Given the unregulated and unsustainable trade of many range-restricted non-CITES amphibian species, a listing of more species on the CITES appendices is required. The IUCN SSC Amphibian Specialist Group is in a position to support CITES parties developing proposals for listing of species with expert advice.

  3. 3.

    In line with recommendations formulated by the Standing Committee of the Bern Convention (see above), appropriate biosecurity needs to be established to assure importation of disease-free animals, in case these originate from countries/regions where particular diseases have been detected. We further suggest that current EU legislation should be strengthened for all non-CITES species along the following guidelines:

  • Restrict or ban trade of species that have been illegally obtained in order to prevent laundering of wild specimens as farmed or captive bred.

  • (Temporarily) Suspend trade until sufficient controls are set up in countries of origin/export and countries of import, and status of exploited populations is monitored sufficiently through independent agencies or certification schemes, for those species that fulfill at least one of the following criteria:

  1. (a)

    Species listed in one of the IUCN Red List of Threatened Species threat categories (Critically Endangered, Endangered or Vulnerable).

  2. (b)

    Species with an extent of occurrence (EOO) of <20,000 km2, or area of occurrence (AOO) of <2000 km2 (IUCN 2012; also cf. Sodhi et al. 2008; Jenkins et al. 2013).

  3. (c)

    Species that are nationally protected in their country of origin.

We believe that these aforementioned guidelines support the need to improve and implement rigorous international standards based on current legislation, taking new scientific knowledge into account. These suggestions will facilitate implementation of improved trade controls in agreement with situations faced by traded species from around the world into Europe, and help conserve amphibian biodiversity globally.