Spawner Recruit Analysis And Escapement Goal Recommendation For Chinook Salmon In The Kuskokwim River Drainage PDF Download

The Susitna River drains approximately 52,000 square kilometers of the southern slopes of the Alaska Range and the Talkeetna mountains. This watershed supports wild populations of all 5 species of Pacific salmon and vibrant sport fisheries when production allows. Chinook salmon spawning escapements have been monitored since the late 1970s by aerial survey and a weir has been used to count returning adults on the Deshka River (a tributary) since 1995. The Deshka River is currently managed by an escapement goal based on weir passage whereas several other spawning populations are managed using escapement goals based only on once-per-year aerial surveys. Other fishery data, such as inriver and marine harvest estimates, age estimates, recent mark–recapture abundance estimates, and spawner distribution data are also available. We present a state-space model that incorporates all available datasets to generate annual inriver and spawning escapement abundance estimates of 4 stocks of Susitna River Chinook salmon. These stocks were created by dividing the drainage into geographical units similar to existing management units used in Alaska Department of Fish and Game sport fishing regulations: Deshka River, Eastside Susitna, Talkeetna River, and Yentna River. The state-space model estimates a spawner-recruitment (S-R) relationship for each stock that is used in developing escapement goal recommendations based on the number of spawners that provide maximum sustained yield (SMSY). SMSY was estimated for each stock: 12,564 for Deshka River; 12,971 for Eastside Susitna; 10,570 for Talkeetna River; and 13,614 for Yentna River. We used a decision matrix to choose escapement goals based on the probability of achieving maximum sustained yield for the 4 stocks. We recommend discontinuing escapement goals for individual spawning populations within these stocks and replacing them with stock-based escapement goals of 9,000–18,000 for Deshka River, 13,000–25,000 for Eastside Susitna, 9,000–17,500 for Talkeetna River, and 13,000–22,000 for Yentna River stocks.