American Bullfrog
Lithobates catesbeianus, Rana catesbeiana
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Introduction
Of particular concern to environmental conservation efforts in the western USA is the importation of several million American Bullfrogs each year, for use in the food, pet and dissection trades. American Bullfrogs are the largest frog species in North America. Bullfrogs are native to eastern North America, but have established populations throughout the western USA, where they cause massive ecological damage due to their voracious appetites for native wildlife; their propensity to spread deadly diseases; and their role as competitors with native amphibians for limited food resources. Bullfrogs are listed on the IUCN's list of 100 worst invasive species (Lowe et al. 2000).
The eradication of bullfrogs from critical amphibian habitat is an integral part of the management plans for many threatened amphibian species in the western USA (D'Amore et al. 2009). However, efforts to eradicate bullfrogs will be futile in the long-term so long as bullfrogs are still being imported into the states to which they do not belong, as the frogs inevitably escape into the wild or are intentionally set free. Thus the continued importation of American Bullfrogs into the western USA runs contrary to state and federal Endangered Species Acts and is in the worst interest of western states' ecosystems and native wildlife.
SAVE THE FROGS! supports a ban on the importation, sale, release and possession of American Bullfrogs into and within areas to which they do not belong, i.e. anywhere outside eastern North America. SAVE THE FROGS! requests that teachers and pet seekers not purchase American Bullfrogs or their tadpoles, as either you or the biological supplier has a high chance of being located outside the frogs' native range.
American Bullfrogs: a primary threat to biodiversity worldwide
The invasion of bullfrogs
Bullfrogs were originally introduced to the western United States in the late 1800's to provide an additional source of frog legs after the California gold miners ate the California Red-Legged Frogs (Rana draytonii) to near extinction (Jennings and Hayes 1985). Bullfrogs have many traits that allow them to be perfect invaders outside their native range: female bullfrogs can lay more than 40,000 eggs (Bury and Whelan 1984), and they can occupy a wide variety of habitats, including manmade and natural wetlands, streams, lakes, ponds and temporary pools.
Bullfrogs have become established in California, Oregon, Washington, British Columbia, Colorado, China, Colombia, Cuba, Dominican Republic, France, Haiti, Italy, Jamaica, Japan, Mexico, the Netherlands, Puerto Rico, South Korea, Taiwan, Venezuela and Uruguay. Due to the ease with which they can be farmed, bullfrogs and bullfrog farms have proliferated around the world in recent years. Combined with America's growing appetite for frog legs (we now eat 20% of the world's frog legs, and are the world's third largest frog legs importer), and the increasing use of bullfrogs in the pet and dissection trades, the importation of bullfrogs into California has been on the rise. Upon arrival in the state, some bullfrogs inevitably escape their holding facilities; others are purposely set free by well-intentioned owners. A more insidious problem is the release into the environment of water from the tanks in which the bullfrogs were held -- and the diseases contained therein.
Predation of native species by bullfrogs
Bullfrogs are the largest frog in North America, and they are "gape-limited predators", meaning they eat any living animal that fits in their mouth. As such, they can eat a large variety of native wildlife including frogs, salamanders, birds, bats and snakes. One bullfrog was found with a 33-inch garter snake in its stomach, and bullfrogs are regularly found consuming endangered California Red-Legged Frogs and California Tiger Salamanders. Their voracious appetites are implicated in the declines of more than a dozen North American amphibian species (Casper and Hendricks 2005).
The spread of deadly diseases by bullfrogs
American bullfrogs are a primary contributor to the spread of chytrid fungus (Batrachochytrium dendrobatidis), a potentially lethal skin disease that has decimated Califonia's amphibian populations and driven up to 100 amphibian species worldwide to complete extinction in recent decades. In terms of biodiversity loss, chytridiomycosis is the single worst disease in recorded history -- not just for frogs, but for any known organism. Bullfrogs are raised and transported in high density containers where they share water and climb on each other: perfect conditions for the spread of chytrid fungus, which has waterborne zoospores and infects amphibian skin.
Several million bullfrogs get imported into San Francisco and Los Angeles each year, primarily from China, Taiwan, Uruguay and Brazil, and a recent study demonstrated that up to 62% of these frogs are infected with the deadly chytrid fungus (Schloegel et al. 2009). Importantly, the high prevalence of chytrid infections in the California study was not an anomaly: 96% of the invasive bullfrogs sampled in a Venezuela study were infected (Hanselmann et al. 2004); in a South Korean study, 23% of the bullfrogs were infected, and bullfrogs were the most infected amphibian species in the country (Yang et al. 2009). The chytrid fungus is thought to have originated in Japan, but now infects frogs throughout California (including Santa Cruz and San Mateo counties), and is a primary contributor to the near extinction of the Sierra Nevada Yellow Legged Frogs (Rana sierrae and Rana muscosa; Rachowicz et al. 2006). Different strains of the chytrid fungus exist, and thus further influx of the fungus will inhibit the ability of amphibian species to develop resistance to chytridiomycosis.
"A complete ban on both harvesting native amphibians and importing non-natives is likely the only means of stopping the continued problem of pathogen contamination and over-harvesting of native species".
– Dr. Nina D'Amore, resident amphibian biologist at the Elkhorn Slough National Estuarine Research Reserve
SAVE THE FROGS! delivers 1,189 petition signatures to California government
On September 12th, 2012 SAVE THE FROGS! Founder Dr. Kerry Kriger and Advisory Committee Member Chris Berry delivered 1,189 petition signatures to the California Department of Fish & Game (DFG) in Sacramento. The petition calls on the state to ban the importation, sale and purchase of American Bullfrogs. Dr. Kriger and Mr. Berry discussed the issue with three DFG officials and hope that this accelerates the process of banning the annual importation of millions of bullfrogs into the state.
Please print this petition and collect signatures!
Californians: please left-click this image to get a PDF that you can download, print and collect signatures for. Then send the petitions to us!
Victory!
At the request of SAVE THE FROGS!, on January 24th, 2012 the City of Santa Cruz became the first city in the USA to ban bullfrogs. On February 28th, 2012 the Santa Cruz County Board of Supervisors followed suit and voted unanimously to ban the importation, sale and purchase of American Bullfrogs in the county.
Learn more here and read the press release here.
"Congratulations Dr. Kriger! You have worked long and hard to to be heard. This is hopeful news indeed".
-- Yvonne Adalian, Canada
"Congratulations on this momentous accomplishment Kerry! Blue skies & green lights" -- Richard Karst
"Congratulations My Dear Dr Kriger for this achievement. Efforts of yours and members of advisory committee are highly appreciated in this regards"
-- Professor K.K.Sharma; MDS University, Ajmer, Rajasthan, India
"Awesome job! Thank you for caring enough to make a difference. This is fantastic, Dr. Kriger." -- Brenda Morris
Below are links to the City and County codes pertaining to American Bullfrogs:
-- Chapter 8.16.070 SALE OR ADOPTION OF DOGS, CATS AND OTHER ANIMALS
-- Chapter 6.18 AMERICAN BULLFROG PROHIBITIONS
SAVE THE FROGS! on Seattle's King 5 News
Gary Chittim of Seattle's King 5 News interviewed SAVE THE FROGS! Founder & Executive Director Dr. Kerry Kriger about invasive bullfrogs, chytrid fungus and other frog issues. Watch it below!
Solution
There ought to be a law banning the importation (and sale) of American Bullfrogs into (and within) the state of California.
Amphibians face an abundance of threats in the 21st century. Some, like global warming, habitat destruction and pesticide usage are extremely difficult to contend with due to logistical, economic, and or social barriers. Conversely, halting the importation of American Bullfrogs into the state is relatively simple, yet serves as an extremely important step towards protecting California's natural heritage for current and future generations.
The proposed law would serve two purposes:
(1) Prevent new bullfrogs and their diseases from entering the state of California; and
(2) Drastically reduce the likelihood that California residents who currently own bullfrogs will pursue large-scale bullfrog breeding or distribution activities.
Proposed language:
WHEREAS, American Bullfrogs (Rana catesbeiana; also known as Lithobates catesbeianus) are not native to California; and
WHEREAS, American Bullfrogs are widely regarded as one of the world's most harmful invasive species; and
WHEREAS, American Bullfrogs cause significant and lasting damage to California's ecosystems by preying on native wildlife, spreading harmful infectious diseases, and competing with native wildlife for limited food resources; and
WHEREAS, California taxpayers are forced to pay for efforts to eradicate or manage feral American Bullfrog populations; and
WHEREAS, American Bullfrogs delay or prevent the recovery of many of California's legally protected endangered species, such as the California Red-Legged Frog and California Tiger Salamander; and
WHEREAS, we believe in the right of children to see, hear and catch amphibians in their native habitat, and the presence of American Bullfrog populations forms a significant obstacle to amphibian conservation efforts in California;
NOW, THEREFORE, I, Joe Simitian do hereby call for a ban on the importation and sale of American Bullfrogs into and within the STATE OF CALIFORNIA, and I call this observance to the attention of all our citizens.
Similar legislation
Legislative Summary: America is far behind the rest of the world in protecting its native wildlife from American Bullfrogs, but the legislation proposed herein will set California ahead of the rest of the United States, and will serve as an important precedent that other states in the western United States will be likely to follow.
While we know of no states with legislation banning the importation and/or sale of any non-CITES amphibian species, a wide and growing body of such legislation exists around the world, and related (albeit temporary) measures were recently enacted in California:
--In March 2010, the California Fish and Game Commission voted unanimously to stop issuing permits for the importation of non-native frogs and turtles into the state for use as food, and in May 2010, the Commission held a "re-consideration" hearing and upheld the motion. American Bullfrogs were the primary culprit that the Commission was acting to control. This sets an important precedent, as California is the first state in the USA to enact such restrictions. Unfortunately, the composition of the Commission changes regularly and thus these measures are by no means permanent. Furthermore, the Commission's decisions do not restrict the sale of bullfrogs, and thus businesses or amateurs can still conceivably propagate and distribute bullfrogs within the state.
--The European Union banned the importation of American Bullfrogs in 1997. The particular article of legislation is Council Regulation (EC) No. 338/97, which you can learn more about here:
http://ec.europa.eu/environment/cites/legis_wildlife_en.htm
--In 2003, Australia enacted what are perhaps the world's strictest regulations on the importation of non-native amphibians, this being due to the infectious disease chytridiomycosis driving at least seven of Australia's frog species to complete extinction after it was introduced into the country in the late 1970's. Amphibian importation is now allowed only for zoological and laboratory usage, and must be accompanied by certificates demonstrating that stringent disease control measures (including quarantine) have taken place.
--Japan has had an invasive bullfrog problem since 1918; the country banned both their sale and import in 2006.
--South Korea has invasive American Bullfrogs and banned their importation circa 2007.
Economics
Invasive species are not only one of the most significant threats to biodiversity in California and worldwide, they are also one of the most costly: the Nature Conservancy estimates that invasive species cost Americans 120 billion dollars each year. Bullfrog eradication programs are consistently required to manage threatened amphibian populations throughout California. These programs are resource intensive and thus extremely costly to California's taxpayers when local, state and federal wildlife protection agencies are responsible for their implementation. Similarly, the broader missions of non-governmental organizations are hindered by the resources that get squandered in managing feral bullfrog populations. Furthermore, from an economic standpoint, businesses are often negatively affected by the presence of legally protected endangered species on their property as their development options and business activities become restricted. As bullfrogs contribute to native species being listed as endangered, a reduction in California's bullfrog populations provides a significant economic benefit to a wide variety of businesses and entrepreneurs.
Only an extremely small proportion of California's population benefits economically from the trade in American Bullfrogs, this being (1) restaurants and supermarkets that sell frog legs; (2) pet stores; and (3) biological supply companies that sell bullfrogs for dissection purposes. None of these businesses are reliant exclusively on the sale of bullfrogs. On the contrary, bullfrog sales generally constitute only an extremely small proportion of their business. As such, the removal of bullfrogs from their menus or list of products should not present any major economic problem for these businesses.
Santa Cruz Sentinel -- Letter To The Editor
This letter written by Paige Davis of the Santa Cruz High School Save The Frogs! Club appeared in the February 21, 2012 Santa Cruz Sentinel.
Additional Reading
Novel, panzootic and hybrid genotypes of amphibian chytridiomycosis associated with the bullfrog trade. Schloegel et al. 2012 Molecular Ecology
Magnitude of the US trade in amphibians and presence of Batrachochytrium dendrobatidis and ranavirus infection in imported North American bullfrogs (Rana catesbeiana). Schloegel et al. 2009 Biological Conservation
Letter from Dr. Peter Daszak. 2010
Letter from Dr. Whit Gibbons. 2010
Letter from Dr. Pearl Symonds. 2010
Letter from Santa Cruz County Fish & Game Commission. 2011
Letter from Santa Cruz County Board Chairman Mark Stone. 2011
Read our proposal to California State Senator Joe Simitian here. 2010
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American Bullfrog - Rana catesbeiana