Document Details Page

ABSTRACT The California Department of Fish and Wildlife's Trinity River Project conducted tagging and recapture operations from July 2012 through March 2013 to obtain adult spring-run (spring Chinook) and fall-run (fall Chinook) Chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch), and fall steelhead (O. mykiss) run-size, angler harvest, and spawner escapement estimates for the Trinity River basin. The information from Task 1 is used by the Trinity River Restoration Program (TRRP) to evaluate program objectives outlined in the Integrated Assessment Plan (TRRP, 2009) Two weirs installed in the main stem Trinity River near the towns of Junction City and Willow Creek trapped 2,798 Chinook salmon, 589 coho salmon, 3,620 fall steelhead and 75 brown trout (Salmo trutta). Utilizing a Petersen mark-recapture methodology, and fish tagged at the weirs and recaptured at Trinity River Hatchery (TRH), we estimate 25,617 spring Chinook migrated into the Trinity River basin upstream of Junction City weir. Using tags returned by anglers we estimate 2,138 spring Chinook were harvested, yielding an escapement of 23,479 fish. An estimated 73,666 fall Chinook migrated past Willow Creek weir (WCW), of which an estimated 1,675 were harvested by anglers, yielding and escapement of 71,991 fish. The coho salmon (coho) run-size in the Trinity above Willow Creek was estimated at 18,657 fish, with no coho estimated to have been harvested, leaving an escapement estimate of all 18,657 fish for potential spawning. An estimated 20,611 (8,379 naturally produced and 12,233 hatchery produced) adult fall steelhead returned to the Trinity River basin upstream of WCW. Anglers harvested an estimated 599 adult fall steelhead above the WCW, leaving 20,012 fish as potential spawners.