FISHERY BULLETIN: VOL. 81, NO. 4 



years of the study, the pattern of the GVF values and 

 the maximum GVF attained were similar. The 

 postspawning minimum GVF occurred in October 

 1980 and in September 1981. Increasing GVF values 

 in November of both years were due to the onset of 

 gamatogenesis. Peak GVF values of 0.87 were observed 

 in May of both years. 



Variance in GVF during each sampling period pro- 

 vides a measure of the intrapopulation synchrony of 

 the reproductive cycle. The larger the variance, the 

 greater the variability in the gametogenic condition 

 of individuals during that sampling period. In 

 general, the mussels were most closely synchronized 

 (Le., lowest variance) during the spring months, when 



r&..r a •» 

 *4tk 





M*. 



mm 



c 



■*' 4 



Figure 5. — Photomicrographs of the gonadal stages of male and female Mytilus edulis at 1 25X magnification, a) Inactive male or female (stage 

 0), 9 September 1980, b) early-developing male (stage I), 25 January 1981, c) late-developing male (stage II), 17 March 1981, d) ripe male 

 (stage IH), 15 April 1981, e) spawning male, 22 June 1982, f) recently spent male, 15 July 1981, g) early-developing female (stage I), 22 



736 



