Tern For The Better

Endangered species

Researchers got eye-catching results from this year’s efforts to curb the bite Caspian terns were taking out of endangered salmon runs in the lower Columbia River.

The terns, though more numerous than in years past, ate 4.4 million fewer salmon during the late spring and early summer than they did in 1999, according to preliminary estimates cited by federally funded researcher Ken Collis.

The results could have been much better had it not been for the lawsuit filed by the Audubon Society, Defenders of Wildlife and other groups, he said. The legal action curtailed actions to scare the birds away from one critical nesting area.

To reduce the terns’ impact on salmon, researchers this year concentrated on reducing nesting on Rice Island, roughly 40 miles inland from the river mouth. Over the years a colony of terns had settled on the sandy island, created as a depository for Corps of Engineers dredge spoils from shipping channels.

About 8,000 breeding pairs nested on the island in 1998.

In 1997, Caspian terns nesting on Rice Island consumed between 6 million and 25 million smolts, or 6-25 percent of the smolts estimated to have migrated down the Columbia’s estuary that year.

Among those fish are 12 salmon and steelhead stocks listed under the Endangered Species Act.

This year, the terns were discouraged from Rice Island and encouraged to nest closer to the mouth of the river on East Sand Island. Research indicated the birds on East Sand island would eat a more varied marine diet and consume roughly 40 percent fewer juvenile salmonids.

Researchers estimate the plan resulted in 7.33 million salmon smolts being consumed in the estuary in 2000 compared with 11.75 million in 1999 when the birds were concentrated at Rice Island.