Table 1.— Regression equations for oocytes of several size classes, 

 and some combinations of same, found in prespawned ovaries of 

 Pacific hake from the Strait of Georgia, B.C. 



females in the number of maturing oocytes as their 

 maturity stage advanced towards hydration. This 

 may be both a reflection of the range in stage of 

 maturity among individual females at a common 

 time of collection, and variation among females in 

 the proportion of yolked oocytes destined for hydra- 

 tion and release 



Apparent fecundity taken as the number of yolked 

 oocytes >200 /urn was best expressed by the equa- 

 tion F a = 0.5501FL 3 - 3896 . The averaged female hake 

 in the Strait of Georgia stock (43.3 cm FL) contain- 

 ed an estimated 193,868 yolked oocytes >200 /urn and 

 had a relative apparent fecundity of 382.3 eggs/g. 

 In comparison, an uncommonly large female (80 cm 

 FL) could contain more than 1.5 million yolked 

 oocytes for a specific fecundity of 477 oocytes/g 

 (Table 2). 



Pacific hake in the Strait of Georgia grow rapidly 

 to age 4, showing almost linear growth in length 

 (McFarlane et al. 1983). Thereafter, growth de- 

 creases rapidly and is accompanied by considerable 

 individual variation in annual growth. The largest 

 female in the sample (82 cm FL) was age 18 whereas 

 another female age 15 was only 49 cm FL. Not 

 surprisingly, age was weakly related to apparent 

 fecundity and wide individual differences in ap- 



Table 2.— Total and relative (oocytes/g body weight) fecundity 

 estimates at fork length for unyolked (40-180 ^m diameter) and 

 yolked (200-780 /^m diameter) oocytes found in prespawned 

 ovaries of Pacific hake from the Strait of Georgia, B.C. 



parent fecundity are evident within age classes 

 (Fig. 4). 



Frequency Distributions of 

 Oocyte Diameter in Postspawners 



Gonads of 276 adult Pacific hake, trawl-caught on 

 3 July 1981, were staged superficially for maturity 

 after Foucher and Beamish 1977. All gonads were 

 in postreproductive state The ovaries of 18 of 111 

 females retained for microscopic analysis were dis- 

 tributed within the various maturity states with 

 these results: spent (1), recovering (7), and resting 

 (10). Yolked oocytes (200-500 /mi) were found in 7 

 ovaries: spent (1), recovering (4), and resting (2). 

 Number of oocytes ^200 /mi, expressed as a percent- 

 age of the oocytes <200 pm (40-180 /mi) was <3% 

 in 6 of these fish, and 11% in the seventh, compared 

 with 85-90% in prespawned ovaries collected in 

 March (Table 2). 



These results support previous conclusions that 

 not all yolked oocytes larger than 200 /mi diameter 

 are released, as suggested by Foucher and Beamish 

 (1980) and MacGregor (1966). They also suggest that 

 resorbtion in postspawned females probably does not 

 exceed about 5% of the yolked oocytes destined for 

 release 



The female Pacific hake in the Strait of Georgia 

 appears to use progressively less of the reserve fund 

 of unyolked oocytes present during gonadal matura- 

 tion in subsequent spawnings (Table 2), although 

 relative and apparent fecundity increases with in- 

 creased fork length. This can be illustrated by com- 

 paring females <55 cm FL (Figs. 1, 2) with larger 

 females (Fig. 3). The number of reserve fund oocytes 

 in the size fraction 40-180 /mi increases at a faster 

 rate, almost doubling the relative fecundity for 

 reserve fund oocytes in this size fraction by 80 cm 

 FL than does production of larger oocytes. The 

 reserve fund may have several origins, and cyto- 

 logical evidence was presented by Foucher and 

 Beamish (1980) that the fund may be supplemented 

 by cells of follicular origin in the postspawned ovary. 

 Such a mechanism to increase potential fecundity 

 would appear to be rather redundant if significant 

 resorbtion of yolked oocytes commonly occurs. 



Stock Differences in Fecundity and 

 Estimates of Spawning Stock 



Methodological differences or lack of disclosure, 

 and lack of substantiated assessment of stock- 

 specific resorption following spawning, render it im- 

 possible to draw very useful comparisons of fecun- 



214 



