Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2003

The Tozitna River project is a multi-agency study to determine escapement, run timing, and age–sex–length (ASL) composition of adult Chinook and summer chum salmon in a middle Yukon Basin tributary. A resistance board weir was operated from 23 June to 8 August 2003. High stream discharge from the periods of 2 to 6 July and 26 July to 8 August prevented counting and biological sampling; no interpolation was made for these periods. Comparison of run timing to 2002 and to other tributaries with similar run timing suggests the majority of the Chinook salmon run was counted. The escapement for Chinook salmon was 1,819. Females composed 18% of the overall escapement. Age groups 1.2 and 1.3 accounted for 28% and 52% of the escapement, respectively. The majority of the summer chum salmon escapement was not counted, and ASL composition was determined with partial escapement data. The escapement for summer chum salmon was 8,487, and 34% of the total fish sample was female. Age 0.3 comprised 83% of the chum escapement.