West Fork Environmental is in the third year of a three year study investigating the spatial and temporal distribution of spawning sockeye salmon in the Cedar River between Lake Washington and Landsburg Diversion Dam. Seattle Public Utilities has funded projects to sample sockeye otoliths at the Hiram Chittenden Locks and from broodstock collected for the Cedar River Sockeye Hatchery. Understanding how representative these samples are of the naturally spawning population in the Cedar River will aid in adaptively managing the hatchery.

Sockeye spawn in the Cedar River from late September into January and during this period West Fork staff surveyed the river collecting sockeye carcasses for otolith extraction and analysis. Physical measurements of all carcasses were collected and analysis of these data and origin data (as determined by thermal marks on otoliths) will assess whether the spatial and temporal distribution of naturally spawning sockeye differed for wild and hatchery origin individuals.