That amphibians are the most imperiled class of vertebrates in the world is largely beyond debate. Such threats as habitat loss and overexploitation for meat or the pet trade are decimating amphibian species worldwide.
Each year, hundreds of millions of frogs are eaten domestically or traded internationally for the meat, pet, laboratory research, and dissection markets. While some come from breeding farms—often raised in unhygienic and inhumane conditions, many others are ripped from the wild with significant adverse ecological consequences. Salamanders and newts are also eaten, but they are most coveted for the pet trade. They, too, are removed from the wild in large numbers, with similar impacts to ecosystem health and function.
Indeed, wild amphibians are exploited without any credible information about population numbers or other basic biological information about the species. Without such data, the sustainability of domestic and international trade cannot be assured.
In 2004, Dr. Simon Stuart and colleagues reported in the journal Science that rapid declines in population size have been noted for 435 amphibian species, with habitat loss and overexploitation afflicting 233 of those. The remaining species, many of which were designated as critically endangered, were found to be experiencing “enigmatic” declines. Four years later, in 2008, 38 species were known to be extinct, one was extinct in the wild, 120 species were considered possibly extinct, and 42 percent of amphibian species populations were declining. These numbers, predictably, have only worsened in the past seven years.
Today, according to the International Union for Conservation of Nature (IUCN), at least 41 percent of the 6,424 amphibian species evaluated are threatened (i.e., designated as “critically endangered,” “endangered,” or “vulnerable”). While habitat loss and modification remain the primary global threat to amphibians, climate change, pollution, competition with introduced species, overcollection, and disease are of significant concern. Indeed, for a number of amphibian species, disease has become a particularly acute and deadly threat and likely responsible for the “enigmatic” declines.
Ranaviruses, for example, affect amphibians worldwide and have caused amphibian die-offs in North America, Europe, and Asia, with mortality rates often exceeding 90 percent. Spread of these diseases has been linked to the international amphibian trade and to the use of infected salamanders as fishing bait.
The chytrid fungus (Batrachochytrium dendrobatidis, or Bd) has decimated amphibian populations in the Neotropics, Australian Wet Tropics, western United States, Europe, and East Africa. In Latin America, Bd has been linked to the possible extinction of 30 of 113 species of harlequin toads, while in parts of Panama 41 percent of amphibian species have been lost. Most scientists believe that Bd has been transported around the world by international trade in live and dead amphibians. All told, over 500 amphibian species have been afflicted with Bd, with at least 200 species experiencing significant declines or going extinct due to its effects. Dr. Lee Skeratt of Australia’s James Cook University and colleagues declared in 2007 that “the impact of chytridiomycosis on frogs is the most spectacular loss of vertebrate biodiversity due to disease in recorded history.”
Another chytrid fungus, Batrachochytrium salamandrivorans (Bsal), which is believed to be native to Asia, represents a new disease threat. Bsal’s deadly impacts appear to be restricted to salamanders and newts, with exposed species experiencing significant population declines. In the Netherlands, Bsal caused a 96 percent decline in fire salamander populations in only four years. It has since been detected in amphibians in Belgium and the United Kingdom, where it was detected in captive salamanders imported from both mainland Europe and Asia.
To date, Bsal has not been detected in the Western Hemisphere. The United States is the global hotspot for salamander diversity, with about 190 species, although nearly one-third of them are at risk of extinction. Unfortunately, there is nothing in US law that prevents the importation of infected amphibians. Indeed, according to government data compiled by the Center for Biological Diversity, nearly 159,000 Japanese fire belly newts—a known carrier of Bsal—were imported into the United States from April 2005 to April 2015.
The international trade in dead and live amphibians acts as a global expressway for the transport of these novel pathogens. Internationally, not a single country is believed to have sufficient procedures to prevent the introduction of pathogens deadly to amphibians (and in some cases transmissible to humans) via wildlife shipments.
The scale of imports of amphibians into the United States alone for food and pets is astounding. In a 2009 study published in Biological Conservation, Dr. Lisa Schloegel and colleagues documented that, in the six-year period between January 1, 2000, and December 31, 2005, close to 28 million individual amphibians, plus nearly 7.1 million kilograms of amphibians (which includes live animals, parts, and derivatives) were imported via Los Angeles, San Francisco, and New York.
Shockingly, the Schloegel et al. study revealed that 62 percent of nearly 600 frogs purchased by the authors in the three examined port cities (from shops selling them for human consumption) were infected with Bd. Nevertheless, ranid imports have continued; in 2013, more than 3 million live frogs were brought into the United States—more than 1.5 million of them via San Francisco, Los Angeles, and New York. All told, nearly 3.9 million live amphibians (all species) were imported into the United States for the food, pet, and scientific markets in 2013—each potentially carrying dangerous pathogens.
To make matters worse, many wild caught amphibians perish before and during export as a result of injuries sustained during capture and handling, poor care, stress, and disease. Even if they survive shipment, amphibians destined for the pet market in the United States are often warehoused in crowded, unhygienic conditions, with inadequate care.
In late 2009, for example, animal care and law enforcement authorities in Texas were called upon to investigate claims of massive animal cruelty and mortality at US Global Exotics (USGE), an international pet wholesaler. Ashley et al., writing in the Applied Journal of Animal Welfare Science, report that approximately 80 percent of the more than 26,400 animals confiscated during a subsequent raid on USGE facilities were deemed grossly sick, injured, or dead, with the remainder in suboptimal condition. According to USGE records, nearly 3,500 deceased or moribund animals, primarily reptiles, were being discarded every week, resulting in a six-week stock turnover mortality rate of 72 percent.
This massive death rate was a product of poor hygiene, inappropriate housing, lack of enrichment, crowding, and no reliable provision of food, water, heat, and humidity—which in turn led to cannibalism, crushing, dehydration, emaciation, hypothermic stress, infection, and starvation. Remarkably, when those responsible for this carnage went to trial, their defense cited expert evidence that a 72 percent mortality rate was in accordance with wholesale pet industry standards of 70 percent. It should be further noted that this mortality rate doesn’t include the many premature deaths of amphibians after they are sold as pets.
While the statistics on the plight of amphibians are dismal, it’s not all bad news. In the Greater Mekong Region—covering portions of Cambodia, Laos, Myanmar, Thailand, and Vietnam—16 new amphibian species were discovered in 2014, including the color-changing thorny frog (Gracixalus lumarius), a new species of crocodile newt (Tylototriton shanorum), and the pretty (or “pigmy”) narrow-mouth frog (Microhyla pulchella). Just as these species are found, however, their habitats are in peril—threatened by flooding due to dam construction, roads and other infrastructure development, climate change, and collection for the pet and traditional medicine markets.
Half a world away, in Brazil, seven new species of miniature frogs in the genus Brachycephalus were found high on mountaintops within the cloud forests of the Brazilian Atlantic Rainforest. Sadly, many of these brightly colored frogs, smaller than the average human thumbnail, are already under threat due to illegal deforestation and cattle ranching, which destroys the frogs’ habitat.
In addition, for any newly discovered species, overexploitation for the pet and traditional medicine markets in particular is a significant threat. With few laws, if any, in place to protect newly identified species, there is virtually nothing to stop the overcollection of such species. Indeed, many scientists are reluctant to publish information about a new species out of fear that the species will immediately be targeted for the pet trade, a fear that has been realized in a number of cases.
In an effort to protect amphibians, AWI joined Defenders of Wildlife, the Amphibian Survival Alliance, and the Singapore Zoo in hosting joint international amphibian trade workshops in Washington, DC, and Singapore in March 2015. Some of the world’s leading amphibian experts were assembled to identify amphibian species (such as the Kurdistan spotted newt, tomato frog, and the Panamanian golden frog) most at risk from trade for the meat and pet markets, habitat loss, and disease, and to develop species or taxon-specific conservation actions.
Potential conservation actions include strengthening national laws and regulations, enhancing law enforcement efforts, adding to or up-listing species on the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) appendices (to prohibit or regulate and monitor international trade), improving compliance with existing CITES requirements for species already listed, enhancing trade monitoring, and—for species linked to disease threats—developing strategies to reduce the risk of disease transmission and spread.
Such actions are likely to benefit these priority species. But to permanently protect the world’s remaining amphibians, governments must urgently act to embrace amphibian conservation as a national mandate, strengthen laws and the capacity to enforce them, fully comply with existing international mandates, and initiate demand-reduction campaigns. The public can also help by not purchasing amphibians for pets or food and demanding that their governments undertake immediate efforts to stem the loss of amphibians nationally and worldwide.