Commercial Salmon Fisheries
Taku River Fishwheels - Sockeye Counts
Fish wheels on the Taku River are an essential platform for the sockeye salmon mark-recapture program, which provides inseason and postseason escapement estimates. Because fish wheel catchability can be affected by factors such as water level, fish size, abundance, daily spin time, etc., daily fish wheel catches do not necessarily have a meaningful relationship with upriver abundance. In 2018 fishwheel operation protocols were revised and now spin 18 hours a day instead of 24 hours.
Taku Management Model
Note: The capture-recapture estimate is based on inseason information; as the season progresses the estimate will become more reliable because more data will be available to inform the estimate. Early season, the terminal run estimate is primarily based on a projection using the 10-year average fish wheels run timing and by the end of season it is mostly based on real-time data.
|Pooled Petersen Estimate|
|Current inriver run||100,283||98,471|
|Projected inriver run||134,491||132,061|
|Projected U.S. commercial catch Taku fish||9,112||9,112|
|Projected personal use catch Taku fish||1,500||1,500|
Bilateral capture-recapture data for Taku River sockeye salmon through day 3 of statistical week (SW) 32 (August 4) includes 1,930 tags released, 8,625 fish inspected, and 128 recoveries. Bayesian Time Stratified Population Analysis Software (BTSPAS) was used to generate a pooled Petersen (PP) inriver run estimate of 98,471 (SE=11,044) sockeye salmon and a BTSPAS inriver run estimate of 100,283 (SD=13,720) sockeye salmon. These estimates have been adjusted for tag dropout and size selectivity of gear as per recommendations from the Transboundary Panel and the combined 2020 inseason adjustment is 22% downwards. Using ten year average Canyon Island fish wheel sockeye salmon run timing to August 4 (75%), we project an inriver run of 132,061 sockeye salmon using PP or 134,491 sockeye salmon using BTSPAS. Using harvest estimated through SW 32, the 2020 terminal run of Taku River sockeye salmon is projected to be 142,673 fish using PP and 145,103 fish using BTSPAS.
This estimate compares with a 2020 preseason terminal run forecast of 139,000 fish and a ten-year average terminal run size of 148,000 fish.
The Taku River sockeye salmon escapement goal range is 40,000 to 75,000 fish, with a management objective of 58,000 fish.