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Ecology and salmon related articles

Terns' Diet a Question After Move Down River

by Associated Press
Spokesman Review, April 12, 2002

Salmon eating birds to be pushed closer to Pacific Ocean

VANCOUVER, Wash. -- The world's largest colony of Caspian terns is settling in for another summer on a wind-swept island near the mouth of the Columbia River.

Upstream, millions of juvenile salmon will be making their way toward the ocean, passing by the hungry seabirds nesting on Rice Island.

No one is sure whether the fish-eating terns can change their salmon diet, but a settlement earlier this month between environmentalists and the government cleared the way for the Army Corps of Engineers to move the birds to an island farther down the river so the young salmon have a better chance of making it to the sea.

The corps created Rice Island out of dredge dumpings from the main shipping channel in the Columbia. The terns soon flocked to the 230-acre island to nest during their annual migration from Central America, moving upriver to dine almost exclusively on salmon and steelhead smolts.

But the Audubon Society and other conservation groups have agreed to allow government contractors to chase the birds 15 miles downriver to East Sand Island, where it is hoped the terns will feast on a more diverse diet of ocean delicacies such as perch, anchovies and sculpin.

In return, the government agreed to conduct long-term studies on the birds and come up with a management plan.

"That's the next stage of this work," said Ken Collis, a researcher involved in counting the terns and studying their diet. "To not only help fish, but terns as well. Everybody's on the same page now."

This week, a tractor and bulldozer were sent in to clear six acres on East Sand Island for the tern migration.

Researchers estimate terns devoured 11 million salmon and steelhead smolts in 1998 -- a big chunk of the 95 million to make it as far downstream as the Columbia River estuary.

Despite the toll the birds take on the salmon, some researchers are concerned the birds may actually help the fish by culling weaker hatchery-raised smolts, which tend to feed near the surface and make easy pickings for the dive-bombing terns.

Related Sites:

Associated Press
Terns' Diet a Question After Move Down River
Spokesman Review, April 12, 2002

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