Estimates of total annual return of Chinook salmon to the Kuskokwim River, 2002–2007

Alaska Department of Fish and Game, Fishery Data Series No. 12-36, Anchorage

Chinook salmon Oncorhynchus tshawytscha abundance in the Kuskokwim River drainage from 2002 through 2007 was estimated by combining harvest estimates, escapement estimates in monitored tributaries and expansions to unmonitored drainage areas, and abundance estimates obtained from large-scale mark–recapture studies. Middle and upper Kuskokwim River Chinook salmon abundance was estimated using data from mark–recapture and radiotelemetry studies conducted from 2002 through 2006. We extended the radio telemetry mark–recapture investigation through 2007 and tested assumptions necessary to include recapture data from the Aniak River population in the estimate. Specifically, operation of an escapement monitoring weir on the Salmon River, a tributary of the Aniak River, provided sufficient recapture data to more completely test our mark–recapture assumptions. Estimates of abundance above Birch Tree Crossing (rkm >294) ranged from 125,235 to 245,043 Chinook salmon. Additionally, we estimated escapement in the lower Kuskokwim River tributaries using weirs and a habitat-based model. Estimates of escapement in the lower Kuskokwim River ranged from 46,925 to 105,118 Chinook salmon. Combining these estimates with harvest data provided estimates of the total Chinook salmon run to the Kuskokwim River for the years 2003 through 2007 ranging from 241,617 to 422,657 fish.