Columbia/Snake Survival Rates Mixed For Juvenile Fish
Estimated survival rates for this year's spring-migrating juvenile fish passing through the Columbia and Snake river system show a mixed bag of results.
Paul Wagner of NOAA Fisheries shared 2016 preliminary survival estimates for 2016 with the Fish Passage Advisory Committee meeting Oct. 4, and at the Technical Management Team meeting the following day.
The 2016 report by the Northwest Fisheries Science Center covers juvenile spring Chinook, steelhead and sockeye moving downstream on the Snake and Columbia rivers April 1-June 15.
Wagner said most Snake River hatchery spring Chinook survived to Lower Granite Dam at higher levels than the 10-year average.
However, estimated survival to Bonneville Dam of the combined Snake River hatchery and wild-yearling Chinook fell slightly below the long-term average, the 22-page memo said. From the Snake River trap to the Bonneville Dam tailrace, the survival rate was 33 percent.
The survival study, based on PIT-tag data, started in 1993 and is funded by BPA.
It was a similar story for Snake River hatchery and wild steelhead. Their survival was above-average through the Snake system, but the combined steelhead survival estimate from the Snake River trap to the Bonneville tailrace was 44.4 percent below average.