Silent Streams: Escalating Endangerment for US Freshwater Fishes

Silent Streams? Escalating Endangerment For North American Freshwater Fish

http://www.sciencedaily.com/releases/2008/09/080909205412.htm
http://www.sciencedaily.com/releases/2008/09/080909205412.htm

An endangered holiday darter (Amicola population). Darters are among the most
threatened Southeastern fish; they have been likened to aquatic canaries.
(Credit: Photo by Noel Burkhead, USGS)ScienceDaily (Sep. 10, 2008) — Nearly 40
percent of fish species in North American streams, rivers and lakes are now in
jeopardy, according to the most detailed evaluation of the conservation status
of freshwater fishes in the last 20 years.

The 700 fishes now listed represent a staggering 92 percent increase over the
364 listed as "imperiled" in the previous 1989 study published by the American
Fisheries Society. Researchers classified each of the 700 fishes listed as
either vulnerable (230), threatened (190), or endangered (280). In addition, 61
fishes are presumed extinct.

The new report, published in Fisheries, was conducted by a U.S. Geological
Survey-led team of scientists from the United States, Canada and Mexico, who
examined the status of continental freshwater and diadromous (those that migrate
between rivers and oceans) fish.

"Freshwater fish have continued to decline since the late 1970s, with the
primary causes being habitat loss, dwindling range and introduction of
non-native species," said Mark Myers, director of the USGS. "In addition,
climate change may further affect these fish."

Most Vulnerable Groups

The groups of fish most at risk are the highly valuable salmon and trout of the
Pacific Coast and western mountain regions; minnows, suckers and catfishes
throughout the continent; darters in the Southeastern United States; and
pupfish, livebearers, and goodeids, a large, native fish family in Mexico and
the Southwestern United States.

Nearly half of the carp and minnow family and the Percidae (family of darters,
perches and their relatives) are in jeopardy. Fish families important for sport
or commercial fisheries also had many populations at risk. More than 60 percent
of the salmon and trout had at least one population or subspecies in trouble,
while 22 percent of sunfishes — which includes the well-known species such as
black bass, bluegill and rock bass — were listed. Even one of the most popular
game species in the United States, striped bass, has populations on the list.

Regions with the Most Troubled Fish

Regions with especially notable numbers of troubled fish include the
Southeastern United States, the mid-Pacific coast, the lower Rio Grande and
basins in Mexico that do not drain to the sea.

Hotspots of regional biodiversity and greatest levels of endangerment are the
Tennessee (58 fishes), Mobile (57), and the southeastern Atlantic Slope river
systems (34). The Pacific central valley, western Great Basin, Rio Grande and
rivers of central Mexico also have high diversity and numbers of fish in peril,
according to the report. Many of the troubled fish are restricted to only a
single drainage. "Human populations have greatly expanded in many of these
watersheds, compounding negative impacts on aquatic ecosystems," noted Howard
Jelks, a USGS researcher and the senior author of the paper.

Degree of Trouble

Of fish on the 1989 imperiled list, 89 percent are either still listed with the
same conservation status or have become even more at risk. Only 11 percent
improved in status or were delisted. The authors emphasized that improved public
awareness and proactive management strategies are needed to protect and recover
these aquatic treasures.

"Fish are not the only aquatic organisms undergoing precipitous declines," said
USGS researcher Noel Burkhead, a lead author on the report and the chair of the
AFS Endangered Species Committee. "Freshwater crayfishes, snails and mussels are
exhibiting similar or even greater levels of decline and extinction."

The authors noted that the list was based on the best biological information
available. "We believe this report will provide national and international
resource managers, scientists and the conservation community with reliable
information to establish conservation, management and recovery priorities," said
Stephen Walsh, another lead author and USGS researcher.

This is the third compilation of imperiled, freshwater and diadromous fishes of
North America prepared by the American Fisheries Society's Endangered Species
Committee. Additional information is available at http://fisc.er.usgs.gov/afs/

Adapted from materials provided by United States Geological Survey.