. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder . i_l ! I I I I I I â I I I 20 25 40 45 Fork Length (cm) Figure 33-14. Length-maturity relationships observed from pollock taken during the April-June 1976 demersal trawl survey (Bakkala and Smith 1978). TABLE 33-6 Characteristics of the grovi^th of walleye pollock, based upon NMFS Crab-Groundfish research vessel surveys, 1973-1978. Age^ Mean body^ Mean body^ Relative age class'* (yrs) length (cm) weight (g) weight (g) X Yx Wx IxWx 3.
. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder . i_l ! I I I I I I â I I I 20 25 40 45 Fork Length (cm) Figure 33-14. Length-maturity relationships observed from pollock taken during the April-June 1976 demersal trawl survey (Bakkala and Smith 1978). TABLE 33-6 Characteristics of the grovi^th of walleye pollock, based upon NMFS Crab-Groundfish research vessel surveys, 1973-1978. Age^ Mean body^ Mean body^ Relative age class'* (yrs) length (cm) weight (g) weight (g) X Yx Wx IxWx () () () () () () * Assuming a median birthday of April 1. ^Overall observed mean fork lengths. The lengths in paren- theses were based upon limited observations. ^Overall mean predicted body weights (wet tissue). '* Computed as the product of "survival" times "mean body" weight. relationship between "fork length" and "proportion of individuals sexually mature" was best described by a sigmoidal curve of the model: P = e be -cL (4) where P is the proportion of the apparent population mature at size L cm, e is the natural constant , and b and c are constants. The fitted model for male pollock was found to be (Fig. 33-14): p = gâ; .224L (5) and the length at which 50 percent of the individuals were mature was cm. Female pollock matured at longer lengths than males, and the fitted model was: .209 L p = gâ (6) with the length at 50 percent maturity equal to cm. In the eastern Bering Sea, the sexually mature fraction of the pollock population undergoes a
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