2018 Conservation and Science Report Five

PERSPECTIVE

Snake River Salmon and Steelhead Abundance

The following links to graphs produced by Idaho Fish and Game track the run size of hatchery and wild salmon and steelhead passage above Lower Granit Dam, comparing it to recovery goal for these threatened species from the 1950s to 2017. The spring and summer chinook were protected through the Endangered Species Act in 1992 and the steelhead since 1997. Based on average age for returning adults for steelhead, A-run would be 7 generations and for the B-run 5 generations since they were protected by the ESA.

What these graphs do not show is the wild spawner abundance (escapement) for these two species. These threatened animals are theoretically being managed for recovery by the National Marine Fisheries Service along with cooperation by state and tribal fishery agencies through federal permits.

Factors limiting the recovery of wild salmon and steelhead certainly include the protection of spawning and rearing habitats, migrational habitat (included dam associated mortality and protection of thermal sanctuaries for migrating fish), harvest by various fisheries (including spawner escapement criteria by natal stream) and hatchery impacts (including genetic and ecological problems related to naturally spawning hatchery fish).

Since these wild ESA-protected species are not showing signs of recovering after 21 years of ESA protection, it is evident that too few wild spawners are reaching their natal rivers (escapement), because wild salmon and steelhead are not managed for spawner abundance and egg deposition criteria to fill habitat capacity by natal river. However, hatchery salmonids are managed with specific criteria for adult spawners and egg take to fill the productive capacity of each hatchery.

#5 CONSERVATION AND SCIENCE REPORT

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