. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder. Oceanography Bering Pacific herring 515 LENGTH VS AGE OF PACIFIC HERRING 300-1 250- 200 150 100 Port Clarence Norton Sound Togiak SE Alaska. "1 r- r 4 6 Age 10 Figure 32-5. Size-at-age comparisons of Pacific iierring from selected areas in the eastern Bering Sea and tiie nortlieastern Pacific Ocean. The parameters of von Bertalanffy's equation are: L„ (maximum length in mm) = , K (growth rate) = , and to (age in years, fish was 0 length) - Warner (1976) compute
. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder. Oceanography Bering Pacific herring 515 LENGTH VS AGE OF PACIFIC HERRING 300-1 250- 200 150 100 Port Clarence Norton Sound Togiak SE Alaska. "1 r- r 4 6 Age 10 Figure 32-5. Size-at-age comparisons of Pacific iierring from selected areas in the eastern Bering Sea and tiie nortlieastern Pacific Ocean. The parameters of von Bertalanffy's equation are: L„ (maximum length in mm) = , K (growth rate) = , and to (age in years, fish was 0 length) - Warner (1976) computed a von Bertalanffy curve for fish captured in trawl samples in Bristol Bay. His coefficients were L„ = 299, K= , and t^ = These estimates, although lower, do not differ signifi- cantly from Shaboneev's data, given the VEiriances reported by Warner. Mortality Beyond the larval stage the rate of natural mortal- ity decreases sharply and continues to decrease slightly until about age five, when it begins to in- crease from senility, disease, and spawning mortality (Fig. 32-6). The magnitude of mortality in the juvenile stage is actually unknown but inferences from other fish populations suggest that it is highest in years of high egg and larval survival because of intense intraspecies food competition (Ricker 1975). A general estimate of the natural mortality rate for eastern Bering Sea herring was derived by Wespestad (1978a), using the procedure of Alverson and Carney (1975). This method estimates the natural mortality rate for eastern Bering Sea herring to be Nat- ural mortality can also be determined by an analysis of catch curves using regression techniques (Ricker 1975). Applying this method to data presented by Laevastu and Favorite (1977), we have determined the instantaneous mortality rate for fully recruited ages of eastern Bering Sea herring to be Age- specific natural mortality estimates are unavailable for the eastern Bering Sea stocks; howe
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