February 20, 2009

WASHINGTON (AP) -About four out of 10 freshwater fish species in North
America are in peril, according to a major study by U.S., Canadian and
Mexican scientists. And the number of subspecies of fish populations in
trouble has nearly doubled since 1989, the new report says.

One biologist called it "silent extinctions" because few people notice the
dramatic dwindling of certain populations deep in American lakes, rivers and
streams. And although they are unaware, people are the chief cause of the
problem by polluting and damming freshwater habitats, experts said.

In the Great Lakes, four native species are extinct, three are possibly
extinct, two species are threatened and eight are vulnerable, according to
the study. The extinct species include the Arctic grayling, blue pike,
harelip sucker and deepwater Cisco. All of the Great Lakes species listed as
extinct or vulnerable were harmed long ago by excessive fishing, logging
practices and dam construction.

The grayling was driven from Great Lakes tributaries in the late 1800s by
logging and excessive fishing; deepwater Cisco were eliminated by high
numbers of smelt and alewives in the mid-1900s; and lake sturgeon, a species
listed as vulnerable, were driven to the brink of extinction in the lakes in
the 1800s and early 1990s by excessive fishing, logging and dams that
eliminated much of their spawning habitat.

Sturgeon are recovering in some parts of the Great Lakes; there is a
resident population in the Muskegon River that dates back to the
pre-settlement era. Repeated efforts to reestablish Arctic grayling in
Michigan rivers have failed.

The study, led by U.S. Geological Survey researchers, was the first massive
study of freshwater fish on the continent in 19 years. An international team
of dozens of scientists looked not just at species, but at subspecies -
physically distinct populations restricted to certain geographic areas. The
decline is even more notable among these smaller groups.

The scientists found that 700 smaller but individual fish populations are
vulnerable, threatened or endangered. That's up from 364 subspecies nearly
two decades ago. And 457 entire species are in trouble or already extinct,
the study found. Another 86 species are OK as a whole, but have subspecies
in trouble.

The study is published in the current issue of the journal Fisheries, the
monthly publication of the American Fisheries Society. Researchers looked at
thousands of distinct populations of fish that either live in lakes, streams
and rivers or those that live in saltwater but migrate to freshwater at
times, such as salmon that return to spawn.

Some vulnerable fish are staples of recreational fishing and the dinner
plate. Striped bass that live in the Gulf of Mexico, Bay of Fundy and
southern Gulf of St. Lawrence are new to the imperiled list. So are snail
bullhead, flat bullhead and spotted bullhead catfish. Sockeye, Chinook,
Coho, chum and Atlantic salmon populations are also called threatened or
endangered in the study. More than two dozen trout populations are
considered in trouble.

About 6 % of fish populations that were in peril in 1989, including the
Bonneville cutthroat trout, have made a comeback, said lead author Howard
Jelks of the U.S. Geological Survey. But one-third of the fish that were in
trouble in 1989 are worse off now, said the Gainesville, Fla., biologist.

The study includes far more species and populations than those that are on
the official U.S. government endangered species list. Jelks said the number
of species in trouble was close to double what he expected and that means
people should be "considerably worried." The biggest cause, Jelks said, is
degraded freshwater habitat, both in quality and quantity of water for fish
to live in. Invasive species crowding out native fish is also to blame, he
said.

Fish "live in a freshwater habitat that's pretty much under assault by
people," said Duke University marine biologist Larry Crowder, who wasn't
part of the study. "Things are tanking all around us. When does it have to
be bad enough to get people's attention?" Many of the species in trouble or
already extinct are small minnows and darters whose absence is little
noticed, but they play a vital role in the food chain.

Hardest hit is Mexico where nearly half the fish species are in trouble. One
in three species in the United States are in peril - up from about one in
five in 1989. About 10 % of Canadian species dwindled. In the United States,
the most vulnerable populations are in the Southeast, not counting Florida.

In the U.S. 263 fish species are in trouble or are already extinct, and
nearly 500 have no problems. The number of fish species and subspecies in
North America that went extinct rose from 40 to 61 since 1989.

Anthony Ricciardi, a McGill University biologist who was not part of the
research, found that about 10 years ago freshwater extinctions were
happening at a faster pace than on land or in the sea. And yet few people
notice, he said. "A lot of silent extinctions are happening," Ricciardi
said. "What we're doing is widespread, it's pervasive and it's rapid."