300 



Fishery Bulletin 105(2) 



1 -1 



Spent 

 Spawning 

 Vitellogenesis 4 

 Viteltogenesis 3 

 Vitellogenesis 2 

 Vtellogenesis 1 

 Cortical alveoli 



Figure 3 



Proportion of Greenland halibut iReinhardtius hippoglossoides) females in each 

 histological maturity stage by month. The number of females (/il is noted for each 

 month along the x-axis. Ovaries were collected in March 2004; June 2000, 2002, 

 2003; July 2000, 2002, 2003; September 1999, 2000; and October 2000. 



The final estimate of instantaneous natural mortality 

 (M) in our study had a standard error of 0.0138, yielding 

 a 95% confidence interval of 0.08-0.14). 



Potential annual fecundity 



When nine females were tested for the difference in mean 

 oocyte density by ovary location, the difference was sig- 

 nificant (two-way ANOVA, P<0.01, df=2 , F=19.7). Mean 

 oocyte densities were 280, 276, and 240 in the anterior, 

 middle, and posterior locations in ovaries, respectively. 

 Paired ^tests indicated that the posterior location had a 

 significantly lower oocyte density than middle (P<0.001) 

 or anterior locations (P<0.001), whereas the middle and 

 anterior locations were not significantly different from 

 each other {P=0.19). Oocyte density was also slightly lower 

 in the eyed (259 eggs/gram) than in the blind lobe (272 

 eggs/gram; two-way ANOVA, P=0.034, df=l, F=4.8). 



Mean oocyte diameters also varied significantly by 

 ovary location (two-way ANOVA, P=0.047, df=2, F=3.4). 

 Mean oocyte diameters for the anterior, middle, and 

 posterior locations were 1611, 1627, and 1609 fim, re- 

 spectively. We observed two distinct and separate oocyte 

 size-frequency modes corresponding to nonvitellogenic 

 and vitellogenic oocytes when the average vitellogen- 

 ic oocyte diameter exceeded 1000 ^tm (Fig.4). On the 

 basis of these results, we decided to include only those 



samples where the mean vitellogenic oocyte diameter 

 was greater than 1000 f<m (n = 6 oocytes per specimen 

 for histological examination). 



Potential annual fecundity data conformed more 

 closely to a linear regression on total weight: 



Fee = 13.438 (Wt,^,Jg)) - 436.4438 ^2=0.6206, n = 47 



where Fee = fecundity; and 



Wt 



total 



= total weight. 



than to a nonlinear regression on length (Fig. 5): 



Fee = 0.0266 (ForkLength(cm))^^^^\ r2=o.4969, «=47 



where Fee = fecundity; and 



ForkLength = fork length. 



The highest fractions of atretic vitellogenic oocytes 

 occurred in females with oocytes in early stages of vitel- 

 logenesis. Once the largest cohort of vitellogenic oocytes 

 reached a diameter of 750 fim, the fraction of atresia 

 was greater than 0.20 for only one of 153 specimens. 

 Over 77% of females with developing oocytes had frac- 

 tions of atresia of 0.05 or less, and over 90% of females 

 had fractions of atresia of 0.10 or less. For fish that 

 met oocyte diameter criteria for fecundity estimates 



