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Biologists Puzzled Over
Low or Late Spring Chinook Run

by Keith Ridler, Associated Press
Seattle Post-Intelligencer, May 5, 2006

BOISE, Idaho -- Fishery managers in the Northwest predicted that 88,000 spring chinook would swim upstream past Bonneville Dam on the Columbia River this year, but with fewer than 20 percent having done so this late in the season, officials are considering revising that number.

"I think it's likely that it will go down," said Cindy LeFleur, a policy coordinator for the Columbia River Compact with the Washington Department of Fish and Wildlife. "(The run) is very late, and we really don't have a good explanation why. It could be less than we predicted."

As of Friday, only about 15,500 spring chinook had gone past the dam. The 10-year average is about 112,000 past the dam for this time of year.

A new prediction on this year's run will be made Monday when managers meet to look at fish counts. Managers say they need to see the peak of the run going past the dam before they can make a good prediction about its size.

In the meantime, a multimillion-dollar sport fishing industry is on hold in many areas while anglers wait for the fish to arrive. Some fishing seasons might not open at all this year.

"Every day that goes by that we don't see a significant increase of fish passage at Bonneville puts us further away from seeing a season," said Sharon Kiefer, anadromous fishery manager for the Idaho Department of Fish and Game. "But we haven't closed the door yet."

By Friday, only 18 spring chinook had gone past Lower Granite Dam - the uppermost of the eight dams between the Pacific Ocean and Idaho by way of the Columbia and Snake rivers. The 10-year average for this time of year is about 18,000 fish.

The last time Idaho didn't have a sport fishing season for spring chinook was 1999. Bill Horton, IDFG anadromous fishery coordinator, said that a 2001 survey found that Idaho anglers going after spring chinook spent $46 million on everything from lures to lodging.

Idaho, Oregon and Washington combine to put about 14.2 million hatchery spring chinook into the Columbia River system each year above Bonneville Dam. About 1 percent or less survive the journey to the ocean and back, fishery managers say.

Of the 88,000 spring chinook predicted to return past Bonneville Dam this year, about 16,000 of them were estimated to have come from wild stock listed as threatened or endangered, said LeFleur.

Most wild and hatchery spring chinook spend two years in the ocean, averaging 8 to 15 pounds when they head back up the Columbia. But some individual fish return earlier and some later, which helps avoid entire year classes being wiped out if conditions for survival are poor. Fish that remain an extra year or two in the ocean grow larger. The record in Idaho is 56 pounds.

Other factors that influence how many fish return include whether young fish heading to the ocean had favorable migration conditions, fewer predators, and good conditions to get past the dams. Ocean conditions also determine how many of the fish find enough food to survive.

"The environment is out of our hands," said John Thorpe, fish propagation program manager for the Oregon Department of Fish and Wildlife.

Sport anglers in the Columbia Basin can most often only keep hatchery fish and must release wild fish unharmed. Hatchery fish have the adipose fin - the fin between the tail and dorsal fin - clipped off to distinguish them from wild fish.

On the Columbia River below Bonneville Dam, sport anglers caught about 5,500 spring chinook this year, LeFleur said, before the season closed early in mid-April due to low numbers of fish going over the dam. A fishery from Bonneville to McNary Dam remained open until April 30.

"But since there were no fish up there it really didn't amount to anything," said LeFleur, who estimated that 20 salmon were caught.

With so few fish going past Bonneville Dam, U.S. Army Corps of Engineers workers last week removed two of the 12 devices designed to keep sea lions out of the fish ladder. But engineers replaced them when they concluded the devices did not seem to be bothering the salmon.

That underscores how unpredictable many fishery managers consider salmon.

"Some things we understand and some we don't," said John North, a fisheries manager with the Oregon Department of Fish and Wildlife who works with the Columbia River Compact. "We don't know why they waited this long, but I think it's a combination of things. The elk didn't drop their antlers until late, the tulips didn't bloom until late, the dogwoods were late. It might all be something we haven't figured out. But hopefully the salmon will keep coming."

Keith Ridler, Associated Press
Biologists Puzzled Over Low or Late Spring Chinook Run
Seattle Post-Intelligencer, May 5, 2006

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