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Forecast of the Kamishak Herring Stock in 1994. Regional Information Report 2A94-12. Alaska Department of Fish and Game, Juneau, Alaska.
The 1994 abundance of Pacific Herring Clupea pallasi in the Kamishak Bay District of Lower Cook Inlet, Alaska, was forecasted for the first time from an age structured analysis model. This model estimates values of survival, maturity, gear selectivity, and initial population abundance that minimize differences between predicted and observed age composition and run biomass estimates. Estimated survival and adjusted initial population abundances were used to project the 1994 abundances. A regression model was used to predict 1994 weight at age from 1993 data. The 1993 aerial surveys of run biomass were interrupted by bad weather. Therefore, the 1993 run biomass estimate was derived from daily aerial survey estimates of biomass divided by an estimate of expected daily proportion, The difference between the run biomass estimate, 32,439 tons, and the harvest, 3,570 tons, was escapement biomass. No late season age composition data was collected during 1993. A biomass of 25 thousand tons of herring is forecast to return to the Kamishak Bay District in 1994. Herring mean weight is predicted to be 189 g. The 1988 year class is forecast to represent 70% of the run biomass and 69% of the individuals. The 1994 recommended total allowable harvest is 3.8 thousand tons and represents an exploitation rate of 15%. In accordance with the Kamishak Bay Herring Management Plan the harvest allocation is 3.4 thousand tons for the Kamishak spring sac roe fishery and 380 tons for the Shelikof Strait fall food and bait fishery. KEY WORDS: Clupea pallasi, herring, forecast, Lower Cook Inlet, age structured analysis