California Endangered Species Act Protection Sought to Save Mountain Yellow-legged Frog From Exotic Trout, Habitat Destruction, and Disease

SAN FRANCISCO - The Center for Biological Diversity
today petitioned the California Fish and Game Commission to list all populations
of the highly imperiled mountain yellow-legged frog as endangered under the
California Endangered Species Act. Mountain yellow-legged frogs
inhabit high-elevation lakes, ponds, and streams in the Sierra Nevada Mountains and Transverse Ranges of California and are on a rapid trend to
extinction. Their rapid decline is due to predation by
introduced trout, spread of diseases
that may be exacerbated by exposure to pesticides, and habitat alterations
caused by climate change, drought, and livestock
grazing.

"Once the most
abundant frog in the high Sierra, the mountain yellow-legged frog now barely
clings to survival," said Jeff
Miller, a conservation advocate with the Center for Biological Diversity. "The
mountain yellow-legged frog needs the protections of the California
Endangered Species Act to have any chance at recovery."

Although mountain yellow-legged
frogs throughout California should be protected
under the federal Endangered Species Act, the U.S. Fish and Wildlife Service has
only listed the Southern California population
as endangered. In response to a 2000 petition filed by the Center for Biological
Diversity, the Service determined that Sierra
Nevada mountain yellow-legged frogs also warrant federal listing as
endangered, but that such listing is precluded by actions to list other species.
As a fallback the agency placed the Sierra population on the candidate list,
which does not confer federal protection. The average time on the waiting list
for candidate species is 17 years, and many animals and plants have gone extinct
while languishing on this list.

"Continued delay of federal
protection for all mountain yellow-legged frog populations is placing this
unique California amphibian at risk of extinction,"
said Miller. "Without federal action, this frog needs protection under the
California Endangered Species Act."

Only a few decades ago, it was
difficult to walk around many of the Sierra's alpine lakes without tripping over
diminutive mountain yellow-legged frogs, known as "mountain gnomes." These hardy
survivors of freezing Sierra winters are vulnerable to a host of modern threats
that have driven the species to the brink of extinction. Surveys since 1995 at
225 historic frog localities show extinction of 93 percent of the northern and
central Sierra populations and 95 percent of southern
populations.

This month the California Department
of Fish and Game released a final environmental impact report on the impacts of
stocking of hatchery fish on mountain yellow-legged frogs and other imperiled
species, which unfortunately failed to adopt sufficient mitigation to protect
the species from the impacts of past and ongoing fish
stocking.

Background

Mountain yellow-legged frogs are
adapted to high-elevation habitats without aquatic predators. Widespread
stocking of nonnative trout in high-elevation Sierra lakes by the California
Department of Fish and Game has been the primary cause of decline for the
species. Introduced trout prey on tadpoles and juvenile frogs and change the
food web of the aquatic ecosystems frogs depend upon. Since 2000, the National
Park Service and U.S. Forest Service have begun removing nonnative trout from
some high Sierra lakes on federal lands in an attempt to restore yellow-legged
frog populations.

In 2006 the Center for Biological
Diversity filed suit against Fish and Game for failing to complete an
environmental review of the impacts of fish stocking on sensitive aquatic
species; in 2007 a court ordered the state
agency to conduct a public review of the stocking program's impacts. In 2008
Fish and Game agreed to interim restrictions prohibiting stocking trout in water
bodies with species sensitive to nonnative fish. Although the state has taken
steps to reduce trout stocking in areas with yellow-legged frogs, stocked trout
continue to harm frog populations and limit recovery. Permanent protection and
management decisions to stop stocking and remove trout in key frog habitats are
necessary to reduce trout predation of mountain yellow-legged
frogs.

Recent research has linked
pesticides that drift from agricultural areas in the Central Valley to declines
of native amphibians in the Sierra Nevada. Pesticides and other pollutants can
directly kill frogs and also act as environmental stressors that render
amphibians more susceptible to diseases, including a chytrid fungus that has
recently ravaged many yellow-legged frog populations.

Mismanagement of national forest lands has degraded frog habitat where livestock
grazing, logging, off-road vehicles, and recreational
activity are allowed in frog habitat. Rapid climate change has brought
warmer temperatures, decreases in runoff, shifts in winter precipitation
in the Sierra from snow to rain, and habitat changes that are rendering frog
populations more vulnerable to drought-related extinction
events.

The mountain yellow-legged frog was
recently re-described by scientists as two distinct species: the southern
mountain-yellow-legged frog (Rana muscosa), which occurs in the southern Sierra and
Transverse Ranges of Southern California; and the Sierra Nevada mountain
yellow-legged frog (Rana sierrae), in the central and northern
Sierra.