Trout May Be Killed to Save California Yellow-Legged Frogs


SAN FRANCISCO, California, November 19, 2009 (ENS) – National Park Service officials in California are about to decide how to kill non-native trout to save critically endangered native yellow-legged frogs. How to eradicate the trout has generated a controversy among environmental groups.

The nonprofit organization Save The Frogs, based in Virginia, is urging the National Park Service to quickly remove the introduced trout from the naturally fishless lakes of Sequoia and Kings Canyon National Parks.

The high mountain lakes in these parks, located in west central California, are some of the last remaining strongholds of the yellow-legged frogs.

These were once the most abundant frogs in California, but they have since disappeared from over 90 percent of their former ponds, due to the introduction of non-native trout, which eat the tadpoles, says Dr. Kerry Kriger, an ecologist who serves as executive director of Save The Frogs.

“The Park Service is currently accepting public comments on whether to remove the trout, so this is an excellent opportunity for average citizens to step up and help protect a critically endangered species,” says Kriger.

Save The Frogs is calling on all citizens to send letters to the National Park Service by November 21 urging the agency to remove the trout from Sequoia Kings Canyon National Park. The group has created a website at where viewers can quickly send their comments to the superintendent.

The trout were brought into these naturally fishless lakes to make the area more attractive to anglers, with the unintended result that the yellow-legged frog is now under consideration for listing as a federally endangered species.

The Park Service says, “Scientists have investigated the role of other causative factors in their decline, such as acid deposition, UV-B radiation, and disease, but predation is clearly the main problem. When fish are present, they eat frogs, force frogs into marginal habitat, and fragment the population.”

There are 560 lakes and ponds within the parks that contain introduced trout, and removal of these non-native species from up to 15 percent of these sites will be considered. Up to 82 lakes and 56 miles of streams are being considered for trout removal.

In its scoping document, the Park Service says the trout removal project “is needed to preserve and restore aquatic ecosystems and populations of native species, including mountain yellow-legged frogs in high elevation lakes and streams, creating new opportunities for visitors to experience native wildlife yet also maintaining recreational fishing opportunities.”

A preliminary project to eradicate trout from 11 lakes in the two parks since 2001 has allowed the recovery of yellow-legged frogs at these lakes. Now Park Service officials want to broaden the campaign to restore the frogs throughout the two parks – while leaving the fish in many lakes that are popular with anglers.

But how should the fish be eradicated?

Environmental groups such as High Sierra Hikers Association, California Trout and Californians for Alternatives to Toxics are opposed to using poison to remove the trout. They say if lakes and streams are poisoned, all gill-breathing creatures, including tadpoles of the yellow-legged frogs, will die along with fish and many insects. Mammals, birds and reptiles are not affected if the poison is applied correctly.

Californians for Alternatives to Toxics says the yellow-legged frogs are being wiped out by agricultural pesticides that drift up to the high mountain lakes that are the frog’s natural habitat.

“Experts with the U.S. Geological Service found agricultural pesticides in the bodies of yellow-legged frogs in wilderness areas of Sequoia National Park a decade ago. Further monitoring by USGS determined the area of the Central Valley where the pesticides had originally been applied before drifting hundreds of miles to the park,” the group says, suggesting that the Park Service use other methods of trout eradication.

Fish also could be captured with nets or killed with electrical shocks, park officials said, but those methods are not workable for larger bodies of water. The poison, which is not harmful to humans, is preferable in those situations, they say.

Initially public scoping was conducted in early 2007, and the Park Service anticipated that a simple environmental assessment would be prepared to analyze the project. As staff began the environmental analysis and re-examined public comments from over 30 different sources, it became clear that the project had the potential for significant impacts on the human environment and was capable of generating controversy.

For these reasons, in early 2009 the superintendent determined that a more comprehensive environmental impact statement would be prepared.

A different superintendent is now in place. In October, the National Park Service named Jeff Bradybaugh, a 27-year veteran of the agency, as acting superintendent of Sequoia and King Canyon national parks.

Dr. Kriger of Save the Frogs is urging quick action to eradicate the predatory trout.

“The amphibian extinction crisis is one of the most significant environmental issues of our time, and it is important for people to understand the causes and extent of the problem, as well as the urgency with which action must be taken if we are to protect remaining amphibian populations,” she says.

Frog populations in California and worldwide have been declining at unprecedented rates, and nearly one-third of the world’s 6,586 amphibian species are threatened with extinction. Up to 200 species have already completely disappeared.

Kriger says amphibians are faced with an onslaught of environmental problems, including climate change, pollution, infectious diseases, habitat loss, invasive species, and over-harvesting for the pet and food trades.

California’s frog populations have been particularly hard hit by pesticides, introduced trout, invasive bullfrogs, and a deadly chytrid fungus that is being transported around the world by human activities.

The public can submit comments on the project until November 21, 2009, online at: http:/, by email at

Before including an address, phone number, email address, or other personal identifying information in comments, the Parks Service says commenters should be aware that their entire comments, including personal identifying information, may be made publicly available at any time.

Copyright Environment News Service (ENS) 2009. All rights reserved.

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