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NW Fishletter #370 June 5, 2017
 Biologists Halve Estimate of Spring Chinook Returning to the Columbia, Later Adjust Number Upward
The Columbia River Technical Advisory Committee cut its forecast for spring Chinook destined for areas above Bonneville Dam in half to 83,000 fish on May 15.
Then May 30, the tribal, federal and state fish biologists said the run size is more likely to total about 118,000 adult fish, which is still smaller than the 160,400 predicted in December.
As of June 4, about 90,000 have crossed Bonneville Dam.
The upriver run includes the Snake River wild spring/summer Chinook and upper Columbia wild spring Chinook, which are Endangered Species Act-listed fish.
Stuart Ellis, a member of the committee, said Chinook sampling in the lower Columbia earlier this spring indicated the fish were present even though they were slow to move upstream.
Biologists have hypothesized that, in part, this year's larger volume of colder-than-normal water, along with increased turbidity, delayed the migration; while the small number of spring Chinook returning is the result of poor ocean conditions in 2015 and 2016 and poor in-river conditions in 2015.
In recent decades the record low return of upriver spring Chinook was set by the 1995 spring Chinook run of 12,790 fish.
As of June 4, not quite 13,000 spring Chinook have passed Lower Granite Dam on the lower Snake River and about 5,000 passed Priest Rapids Dam on the mid Columbia.
So far, this year's spring Chinook runs are less than 50 percent of the 10-year average for returns to the mid-Columbia and the lower Snake River.
Harvests of spring Chinook in the Columbia Basin are similarly depressed for both Indian and non-Indian fisheries. -L. B.
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