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Study to Look at Whether
Cormorants are Harming Salmon Runs

by Associated Press
Seattle Post-Intelligencer, November 1, 2007

LEWISTON, Idaho -- The U.S. Army Corps of Engineers has killed about 10 double-crested cormorants and plans to kill about 30 more on the Lower Snake River as part of a study to see whether the burgeoning population of the fish-eating birds is hindering attempts to bolster threatened and endangered runs of salmon and steelhead.

"Cormorants are moving up river, especially around Lewiston and Clarkston," Scott Dunmire, a fisheries biologist for the corps at Walla Walla, Wash., told the Lewiston Tribune. "Right now we are trying to understand the extent of cormorant expansion up the Snake River. We are trying to determine the scope of our bird predation problem to try to understand the impact of salmon and fish populations."

The double-crested cormorants, pushed nearly to extinction by the now-banned pesticide DDT, are growing at a rate of 8 percent a year, according to a study by the National Audubon Society released last summer.

The birds are about 30 inches long and pursue fish by diving under water. They are protected under the Migratory Bird Treaty Act, but the corps has a permit to kill about 40 cormorants near the mouth of the Snake River. Biologists want to examine their stomachs to see what they're eating.

Dunmire said the birds could be eating shad, but might also be eating juvenile fall chinook that spend the winter in the lower Snake River. He told The Associated Press on Thursday that the permit runs from September through December, allowing biologists to find out what cormorants are eating during that time span.

He said lab tests on the stomach contents of the birds should be completed sometime early next year.

"We are not really sure where these cormorants that overwinter on the Snake River, and are moving toward Lewiston, are coming from," said Dunmire. "Research hopefully will address those questions and give us a better understanding how we can manage our natural resources and maintain a better balance between predators and prey."

He said the research the federal agency is doing could lead to a program designed to reduce cormorant numbers.

"We are really concerned what the impact is on the salmonid population," Dunmire said.

He said the birds aren't native to the area, and are typically confined to coastal areas. He said the birds first arrived at Little Goose Dam on the Snake River about 1995, and have been increasing and expanding ever since.

Carole Vande Voorde, an avid bird watcher, agreed that the birds were rare 10 years ago.

"We would get excited when we saw them, now they are everywhere," she said.

"From all the information I can find, these birds were not here prior to that time period," Dunmire said.

A survey done by the corps in 2004 on a colony of 18,000 cormorants in the Columbia River estuary found that the birds ate 6.5 million juvenile salmon and steelhead that year.

Associated Press
Information from: Lewiston Tribune,
Study to Look at Whether Cormorants are Harming Salmon Runs
Seattle Post-Intelligencer, November 1, 2007

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