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Are Frogs Injurious Species?

The views expressed are those of the author and are not necessarily those of Scientific American.

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Should the sale of frogs and other amphibians be restricted to prevent the further spread of the deadly chytrid fungus? That’s the question the U.S. Fish and Wildlife Service (FWS) is asking, and they want your input.

The chytrid fungus (Batrachochytrium dendrobatidis, or Bd ) has spread around the globe since it was first observed in 1999, putting thousands of amphibian species at risk of extinction. It has already caused the expatriation or extinction of at least 200 species. One of the primary causes of the spread of chytrid fungus is interstate and international trade, for either the pet or restaurant industries, according to Kerry Kriger, founder of Save the Frogs!, a Santa Cruz, Calif.–based foundation.

The chytrid fungus causes a potentially lethal skin disease called chytridiomycosis, which interferes with amphibians’ ability to absorb water and oxygen through their skin. After the fungus hits an amphibian community 80 percent of individuals can be expected to disappear within one year, according to Amphibian Ark. No cure or prevention for the malady exists, although there are methods to help identify it.

FWS agrees that trade is spreading the fungus; the service is now considering listing all live amphibians and their eggs as “injurious wildlife” under the U.S.’s 110-year-old Lacey Act, which regulates the import or transport of wildlife species that are either dangerous to humans or the environment. If the law is invoked, any live amphibians or amphibian eggs would require a health certificate proving they were not infected with chytrid before being transported across state lines or imported into the country. This would not affect any amphibians that people or companies already own, only those about to be transported.

“The new government proposal is fabulous news for frogs, toads, newts and salamanders,” Save the Frogs!’s Kriger said in a prepared statement. “Many of our native amphibian species have little or no resistance to the chytrid fungus. Since there is no known way to eradicate the disease from the wild, we have to keep it from spreading to new populations, and that’s what this proposal intends to do.”

“The worldwide decline of amphibians is of great concern to us,” FWS Acting Director Rowan Gould said in a statement. “We understand that halting the spread of the fungus or eradicating it will take more than just regulating importation and transportation of infected amphibians, but it is a major step in the right direction.”

What happens next? The public now gets its say, and can comment on this proposed regulation until December 16.

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  1. 1. adawson7 5:00 pm 09/22/2010

    I believe that this is idea is great. Many species become endangered because our society waits to take action and before we know it an entire species is wiped out. Since 1999 the chytrid fungus seems to have evolved and can eliminate up to 80% of an amphibian community within a year. The fungus is deadly to the amphibians because it interferes with the amphibians to absorb water and oxygen. Within a ten year period, this fungus has caused expatriation or extinction of at least 200 species. This fungus is approximately killing up 20 different species of amphibians a year. Since there is no cure, the only way to end this outbreak is to put restriction on the interstate and international trade of amphibians.
    The sale of frogs and other amphibians will be restricted not eliminated. This proposal is great because studies have linked the increase of chytrid fungus to the international and interstate trade of the amphibians. This trade is one of the primary causes of the spread. If the law is passed any live amphibians or amphibian eggs would require a health certificate proving they were not infected with chytrid before being transported across state lines or imported into the country. This is not a dramatic change and it will not affect any amphibians that people or companies already own, only those about to be transported. Can you imagine a fungus that would limit the amount of oxygen that we absorb? This would greatly impact us and it is obviously effecting the amphibian population. There is a time to make a change and that time is now for the amphibians. Save the Frogs!

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  2. 2. Eric Mills 10:02 pm 09/26/2010

    ‘Bout time! Let’s make it happen.

    According to a study printed in the April 2009 issue of BIOLOGICAL CONSERVATION, some two million American bullfrogs (commercially raised in Taiwan) are imported into California every year for the live animal food markets (i.e., for human consumption). In this study, of the frogs necropsied, 62% TESTED POSITIVE FOR THE CHYTRID FUNGUS, and a smaller number for the ranavirus. This alone should be enough reason to ban this commerce, no? (The study, by Lisa M. Schloegel, Angela M. Picco, et al., is entitled, "Magnitude of the US trade in amphibians and presence of Batracachochytrium dendrobatidis and ranavirus infection in imported North American bullfrogs (Rana catesbeiana)).

    We’ve been trying for 15 years to convince the California State Fish & Game Commission to stop this trade. We’ve had some 25 necropsies done on the California market frogs and turtles, showing E. coli, salmonella, pasturella, giardia, blood parasites, even one case of malaria. It is ILLEGAL to sell such products for human consumption, yet the trade continues unabated.

    Earlier this year the five-member Commission voted to stop issuing any new permits for the importation of live frogs and turtles for the markets. Unfortunately, the Dept. of Fish & Game is NOT bound to follow the Commission’s instructions, contrary to what most people believe, and the Department seems bent on circumventing the will of the Commission. (And the public: the Commission has received more than 3,500 letters & emails in support of the ban–fewer than a dozen favoring the status quo.) The market turtles (all taken from the wild, depleting local populations in other states) and frogs are commonly purchased alive from the markets and released into local waters. None are native to California, and they pose a major threat to our indigenous wildlife.

    Anyone wishing to help stop this dirty business should contact John McCamman, Director of California Dept. of Fish & Game at 1416 Ninth Street, Sacramento, CA 95814; email –

    The Commission may be reached at the same mailing address; email –

    Eric Mills, coordinator
    email –

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  3. 3. jkodiak 2:39 pm 09/27/2010

    This is a good step. Probably should have been done years ago, but better late than never…
    Patrick Schlemmer
    San Francisco Naturalist Society President

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  4. 4. Vermfly 7:06 pm 11/12/2010

    I fully support these restrictions and bans being placed on frogs being imported for food. As Mr. Mills has stated, scientific studies have shown that American bullfrogs imported for food do often carry chytrid. I know of no current studies that show frogs in the collections of frog hobbyists to carry a high percentage of the chytrid fungus. There is no reason to restrict the trade of all frogs when we know the major species that have been shown to carry it. Focus these restrictions on the food trade where they should be and leave conscientious hobbyists that love frogs alone.

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