FISHERY BULLETIN: VOL. 73, NO. 2 



1970 



OS 



100 



10- 



1971 



FEB ' MAR ' APR ' MAY ' JUN ' JUL ' AUO ' SEP ' OCT ' NOV ' DEC JAN FEB MAR APR MAY JUN JUL AUO SEP OCT NOV OCC JAN 



DSPCNT QpARTIALLr SPENT ■riPE OQ LATE ACTIVE E3 EARLY ACTIVE 



Figure 7.-Gonadal phases and setting of Rangia at station A in relation to salinity from 1970 to 197L The length of each shaded 



area represents the percentage frequency of clams in each category. 



Station C 



The reproductive cycle at station C was similar 

 to that at station B during 1970. However, earlier 

 spawning was indicated by 88% of the clams being 

 either partially spawned or spent in early October 

 (Figure 9). Clams remained in the spent phase 

 until early May 1971, when gametogenesis began. 

 Few ripe clams were found at this upstream sta- 

 tion during the late spring and summer. Clams in 

 the early active phase were found during July and 

 by the end of August all clams were ripe. From 

 September to November 1971 clams were 



predominantly ripe, but there was no spawning. 

 Cytolysis of the eggs began in November, result- 

 ing in a spawned-out appearance (Figure 4D). No 

 spawning occurred at station C during 1971, in 

 marked contrast to stations A and B where the fall 

 spawning was intense. 



Sex Ratio 



The data were divided into summer-fall and 

 winter-spring seasons, because many clams con- 

 tained no discernible gonads during the winter 



I 970 



FEB MAR APR MAY JUN JUL AUO MP OCT MOV DEC ' JAN ' FEB ' MAR ' APR ' MAY ' JUN JUL AU8 SEP OCT NOV OCC JAN 



□ spent Q partially spent Bripe on) late active Oearlt active 



Figure 8. -Gonadal phases and setting of Rangia at station B in relation to salinity from 1970 to 1971. The length of each shaded 



area represents the percentage frequency of clams in each category. 



420 



