September 11, 2008

New Study Finds Freshwater Fish in Increasing Peril


By Seth Borenstein

The Associated Press


About four out of 10 species of freshwater fish in North America are in peril, according to a major study by U.S., Canadian and Mexican scientists.

The number of subspecies in trouble has nearly doubled since 1989, the 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. While they are unaware, people are the chief cause of the problem by polluting and damming freshwater habitats, experts said.

In the first massive study of freshwater fish on the continent in 19 years, an international team of dozens of scientists looked at species and 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 fish populations are vulnerable, threatened, or endangered. That's up from 364 nearly two decades ago.

And 457 entire species are in trouble or extinct, the study found. Also, 86 species are OK as a whole, but have subspecies in trouble.

The study, led by U.S. Geological Survey researchers, is published in the current issue of the journal Fisheries. Researchers looked at thousands of distinct populations that live in lakes, streams and rivers or that live in saltwater but migrate to freshwater at times, such as salmon that return to spawn.

About 6 percent of 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. One-third of those in trouble in ' 89 are worse off , said the Gainesville, Fla., biologist. The study includes far more species and populations than are on the U.S. government endangered list.

Jelks said the number of species in trouble was close to double what he expected.

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 are also to blame, he said.

fish in danger

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.

Originally published by BY SETH BORENSTEIN.

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