Council Weighs in on Tern RelocationColumbia Basin Bulletin - July 30, 1999
The Northwest Power Planning Council last week offered encouragement and advice to federal agencies who are working to relocate Caspian terns that have been making young Columbia Basin salmon the staple of their diets.
"The Council strongly supports elimination of tern nesting habitat on Rice Island, and dispersion of the colony to other sites in 2000," according to a letter sent to the National Marine Fisheries Service, the Corps of Engineers and the U.S. Fish and Wildlife Service.
And the Council made it clear that it felt the birds should be pushed beyond the Columbia's tidal estuary. An initial relocation effort this spring and summer was aimed at moving birds from their preferred nesting site at Rice Island to an island, East Sand, nearer the Pacific Ocean. It was believed the birds nesting at East Sand would encounter and eat more marine fish species, and fewer salmon.
The world's largest colony of Caspian terns, roughly 10,000 pairs, has been settling in recent years on Rice Island. It has been estimated the birds consume from 10 million to 30 million salmon smolts annually, about 10 to 30 percent of the number that survive the trip from river tributaries to the estuary. Included are the progeny of wild salmon and steelhead listed under the Endangered Species Act.
State, federal and tribal resource managers formed a work group last year to devise a relocation plan that would blunt the impact on migrating salmon. Much of the bare sand that terns prefer was covered at Rice Island, by fences and vegetation. East Sand was denuded and decoys and other devices were used to lure terns. And it worked to a great degree.
About 1,800 pairs were drawn to East Sand, and away from Rice Island, according to NMFS' Ben Meyer, chairman of the Caspian tern work group.
The researchers believe it is the "biggest translocation of a bird colony on record," Meyer said. Still, the work group and Council want more.
Preliminary data presented to the Council in late June showed juvenile salmon made up 55 percent of the diet of terns at the newly established colony at East Sand Island. Terns nesting at Rice Island this year chose salmon 84 percent of the time.
"Since the East Sand Island terns still appear to be consuming a significant number of juvenile salmon, the Council believes that the size of that colony" should be limited to 2,000 nesting pairs, the Council's letter reads.
The work group basically agrees. Among the key points in a tentative Year 2000 relocation plan developed by the work group are: 1. elimination of nesting habitat at Rice Island, 2. improvement of East Sand habitat, 3. dispersion of the colony to at least two other locations outside the Columbia River estuary, and 4. additional research on tern diets, distribution, and impacts.
The work group is considering two sites in Washington where terms have nested previously -- two islands in Grays Harbor and another in Willapa Bay. The Willapa Bay site is, essentially, a sand bar that eroded away, Meyer said.
"It may just take some dredge spoils" piled on top of the high point to make the site again appealing to the birds, Meyer said. The group will continue to refine the details and hopefully produce an interim plan by September, Meyer said.
The Council, which provided $235,000 for this year's research, promised to monitor the planning effort. There is a real need to cut down the birds' salmon consumption, Council member Larry Cassidy of Washington said last week. But he said he wanted to make sure the effort did not simply move the problem elsewhere.
"Relocation is a real issue," Cassidy said. "It's like pushing a balloon. You push it in one place and it comes out in another."
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