Spring run of chinook could be worst ever
PORTLAND — At this time of year, the Columbia Basin's fabled spring chinook should be swarming past the Bonneville Dam.
As of Thursday, fewer than 2,300 had swum through fish passages compared with a late-April average of more than 80,000 fish over the past decade.
Biologists still think they will get a late surge of fish — those hopes were kindled by the passage of more than 600 fish on Thursday, compared with fewer than 50 on the same day a week ago. But for the end of April, typically near the peak, this still is a very weak run.
"We definitely have the latest run on record, and we potentially could have the worst on record," said Robert Stansell, an Army Corps of Engineer biologist who monitors fish moving over the dam 40 miles east of Portland.
The spring chinook, a mix of wild and hatchery stock, are packed with oil that gives their flesh a rich taste and fuels a remarkable freshwater migration. Some push deep into Washington, while others, listed as threatened under the federal Endangered Species Act, spawn in Snake River drainages as far as 900 miles from ocean-feeding grounds.
The spring chinook run into June and are followed by other runs of Columbia River Basin summer and fall salmon, which are forecast to arrive in numbers large enough to schedule sport and commercial fishing openings.
But this year's dismal dam count underscores the volatility of the spring chinook runs, which have been one of the focal points of a Columbia Basin salmon-restoration effort that has cost billions of dollars during the past decade.
Scientists believe the ocean, where the fish migrate after their freshwater birth, has a big influence on run size.
Just five years ago, more than 400,000 Columbia Basin spring chinook returned from the ocean in the largest run since construction of the Bonneville Dam in 1938.
The fish benefited from strong seasonal ocean upwellings of nutrient-rich cold water that produced an abundance of food for young salmon. Those upwellings continued for the first few years of the new century along with freshwater conditions that also favored salmon.
"The good news is that salmon runs are up," proclaimed President Bush in an August 2003 stopover at Ice Harbor Dam. "And that's really positive, and we just need to keep the momentum up."
But that momentum has faded in recent years as upwellings weakened, and survival rates of salmon declined.
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Spring run of chinook could be worst ever
