Scientists Propose Ban on All Amphibian Imports to Protect Species From Deadly Fungus

The eastern newt (Notophthalmus viridescens), shown here in its terrestrial red eft, or juvenile, stage, is one of the many American salamander species threatened by the Bsal fungus. Image: Geoff Giller

America has the highest salamander biodiversity of any country in the world. But that incredible natural heritage is threatened by a killer fungus that has already decimated salamander populations in Europe. Now, a dozen scientists who study amphibians and conservation are calling for a total ban on amphibian imports into the United States in an effort to prevent a mass die-off of our nation’s salamanders.

For the past several years, scientists have been scrambling to find a remedy for the deadly fungus—a type of chytrid fungus called Batrachochytrium salamandrivorans, or Bsal for short—while doing whatever they can to prevent it from crossing the Atlantic. If the fungus does end up in the United States, the ramifications could be staggering. In the Netherlands, a population of salamanders declined by 99.9% after Bsal arrived.


Not only would the loss of these fascinating and varied amphibians—which range from a few inches to over three feet long, and are found in almost every state—be a major blow to biodiversity, but salamanders are crucial parts of many food webs. Losing a significant portion of them could be an ecological disaster for many already-strained ecosystems. What’s more, the cost of containing the spread of the fungus would be much larger than preventive costs of keeping it out in the first place.

The government has already taken some steps to protect salamanders. Theres a ban in place on the import of 201 species of salamander, enacted by the Fish and Wildlife Service last year. But now, scientists are saying that that’s not sufficient.

A study recently detected the Bsal fungus on toads collected in the wild in Vietnam and shipped to Europe as part of the pet trade. Another study published earlier this year found that toads could be infected with Bsal in the lab. While researchers suspected that other amphibians might also act as vectors for Bsal, “now we have actual data and evidence,” Karen Lips, who has been studying both types of the amphibian-killing fungi at the University of Maryland and is a signatory on the call for the ban, told Earther.


Frank Pasmans, a professor at Ghent University in Belgium who has been studying Bsal and is a co-author of both studies, told Earther that this “is worrying indeed.” He and his colleagues first realized that Bsal could be infecting toads when fire salamanders in a captive population in Germany started dying off—but those salamanders hadn’t been in contact with any other salamanders. They had, however, been in contact with toads collected in the wild from China or Vietnam.

Pasmans and collaborators in Vietnam tested the same species of toad from wild populations, as well as 36 toads that had been shipped to a German pet store from Vietnam. They found Bsal on 19 wild toads and three captive ones.


Scientists have good reason to be alarmed about Bsal. A closely-related species—another chytrid fungus called Batrachochytrium dendrobatidis, or Bd—has been decimating frog and toad populations around the world for decades, causing numerous extinctions (Bd mostly left salamanders unscathed). Biologists only realized how devastating Bd was after it was already widespread and the damage was irreversible.

“Here is a pretty rare chance to be proactive,” Reid Harris, an emeritus professor of biology at James Madison University and the director of international disease mitigation at the Amphibian Survival Alliance, told Earther.


Harris is one of the scientists calling for the total import ban. Based on the history of Bd, we know “pretty much exactly what’s going to happen” if Bsal gets into the wild in America, Harris said. “It’s going to be like highlands of Panama all over again,” referring to extensive declines of frogs in Panama caused by Bd.

A chytrid-infected frog. Image: Forrest Brem/Wikimedia Commons

When Pasmans and his colleagues infected toads in the lab with Bsal, they found that the toads weren’t actually harmed by the fungus. This might seem like good news, at first. The problem is that frogs and toads can act as conduits, carrying the fungus on their skin to new habitats and spreading it to susceptible salamanders.

This is worrying for several reasons: First, the pet trade in frogs and toads is much larger than that in salamanders, making the overall risk of spread greater. Currently, frogs and toads are still currently coming into the U.S. unchecked for the fungus—any one of them could be the origin of a widespread salamander die-off if it’s carrying Bsal.


“It’s all a game of numbers,” said Pasmans. While it’s possible that a ban on imports into the United States would just drive part of the pet trade underground, it would nevertheless eliminate a lot of the risk, said Pasmans. In Europe, regulations on the trade of salamanders and other amphibians are also under consideration.

“I think it’s a good idea,” Pasmans said of the call for the ban. He thinks most scientists agree the best thing to do about Bsal is prevent it from coming into the country in the first place.


Harris and the other biologists calling for the amphibian ban hope that a “clean trade” program can eventually be established that would help assure that amphibians coming into the U.S. aren’t infected with Bsal. However, they admit that such a framework would be difficult to enact, requiring good lab facilities in different countries around the world. “And we don’t know everything yet about the disease itself, how it works, and how long it takes to manifest,” said Lips. This makes it difficult to create testing protocols.

Should a total ban not be feasible, the scientists recommend either a ban on all amphibian imports from parts of the world where Bsal has been found in the wild, including Germany, Belgium, the Netherlands, Vietnam, Japan, and Thailand, a ban on just certain types of amphibians that are found in those parts of the world, or, at the least, a ban on amphibians on which Bsal has been found or shown to be capable of infecting.


“We have such a rich biodiversity of salamanders in North America, especially in the United States,” said Harris. “It just would be heartbreaking to see these species go extinct.”

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