Stock assessment of the return of late-run chinook salmon to the Kenai River, 1996

Description

The estimated total return of late-run chinook salmon Oncorhynchus tshawytscha to the Kenai River in 1996 was 66,286 (SE = 1,059) fish. This estimate does not include fish harvested in the recreational marine fishery near Deep Creek, which will be estimated by a postal questionnaire with results available in 1997. Total harvest in marine commercial gillnet fisheries (drift and set), the inriver personal use dip net fishery, and Kenaitze Indian educational set gillnet fishery was 12,037 chinook salmon. The total inriver return of late-run chinook salmon was 54,249 (SE = 1,059) fish estimated through hydroacoustic techniques and a creel survey of harvest downstream of the sonar counter. In the downstream section (Cook Inlet to the Soldotna Bridge), angler effort and harvest estimated from a creel survey were 238,495 (SE = 7,285) angler-hours and 5,984 (SE = 404) chinook salmon, respectively. Release mortality from the inriver fishery upstream of the sonar counter was an estimated 64 (SE = 50) chinook salmon. Spawning escapement, which was estimated by subtracting total fishing mortality from total inriver return, was 48,054 (SE = 1,126) chinook salmon and exceeded the optimum spawning escapement of 22,300 stipulated in the management plan. The predominant age class of the commercial harvest, inriver return, and recreational harvest was age-1.4 fish. Migratory timing models were used to project spawning escapement during the 1996 fishery. No additional restrictions to the fishery were required to achieve escapement goals. A relatively strong return allowed for an additional 4 days of recreational fishing in August. Production from the 1984-1988 broods ranged from 0.98 to 2.13 returning fish per spawner. Production from the 1989 brood has been 2.26 returning fish per spawner, with age 8 to return in 1997. Production from the 1990 brood has been 2.09 returning fish per spawner, with ages 7 and 8 to return in 1997 and 1998, respectively. Based on a sibling model, the forecast for the 1997 late-run return to the Kenai River is 120,514 (SE = 32,788) chinook salmon.

Subjects

Series Statement

• Fishery data series -- no. 97-11.

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