HINCKLKY: REPRODUCTIVE BIOLOGY OK WALLEYE POLLOCK 



30 40 



50 60 70 



LENGTH (CM) 



SO 90 



Figure 7. — Observed and predicted relationships between 

 weight and length for walleye pollock from four areas within 

 the Bering Sea. Triangles indicate the weight of the sampled 

 fish. 



Weight-Fecundity Relationship 



The weight-fecundity relationship for walleye 

 pollock in all areas was nearly linear (Fig. 8). The 

 overall test for coincidental regressions indicated 

 that the weight-fecundity relationship differed 

 significantly between areas (F ^ 7.6534, 

 P < 0.001). Comparison of the linearized equa- 

 tions showed that the regression slopes were sim- 

 ilar in the northwest continental slope, the south- 

 east continental shelf, and the southeast 

 continental slope areas (Table 4). The multiple 

 range test on the intercepts of the regressions 

 from the two continental slope areas indicated 

 that they were similar, but different from the re- 

 gression intercept of the line from the southeast 

 shelf area. The multiple range test on the regres- 

 sion slopes showed that the slope of the weight- 

 fecundity regression for Aleutian Basin pollock 

 was similar to that seen in the southeast conti- 

 nental slope area; however, a comparison of the 

 intercepts did show a significant difference be- 

 tween these two areas. 



As with the length-fecundity relationship, the 

 weight-fecundity relationship appeared similar 



in the continental shelf and slope areas, and dif- 

 fered from the relationship seen in the Aleutian 

 Basin. The weight-fecundity relationship for the 

 Aleutian Basin showed the same trend that was 

 seen for length-fecundity, i.e., a much more grad- 

 ual increase in fecundity with weight than in 

 other areas. 



1750 n 



1500 



CO 

 LU 



g 1250 



u. 

 o 



g 1000 



< 



CO 



o 



X 



o 



UJ 



U- 



750 - 



500 



250 



** / 



/ 

 / 



/ 



/ A / 



/ 

 / 



/ «£ SLOfE 



ALEuriAD aula 



500 



1 500 



2500 3500 



4500 



WEIGHT (GM) 



Figure 8. — Observed and predicted relationships between fe- 

 cundity and weight for walleye pollock from four areas within 

 the Bering Sea. Triangles indicate the number of oocytes per 

 sampled fish. 



Ovarian Maturation 



Examination of the egg-stage frequencies indi- 

 cates that the process of ovarian development in 

 Bering Sea walleye pollock (Fig. 9A through 9M) 

 is one of partial synchrony. A "reserve" fund 

 (Foucher and Beamish 1980) of small, unyolked 

 oocytes exists at all times in the ovary; this con- 

 sists of oocytes at the early and late perinucleus 

 stages. The reserve fund is represented by the 

 single mode in Figure 9A. A portion of this group 

 begins the process of yolk formation, advancing 

 asynchronously to the fully yolked tertiary yolk 

 stage (stage 8). This developing mode is visible in 

 Figure 9B, C, and D. When vitellogenesis is com- 

 plete, the mode of developing oocytes is com- 



493 



