FISHERY BULLETIN: VOL. «3. NO. 3 



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Figure 4. -Temperature and salinity variations during the collection period for the four collection sites, 1979 and 1980. 



Although no growth or age measurements were per- 

 formed in this study, the 25 mm shell length in- 

 dicating a lower limit to sexual maturity corresponds 

 to the east coast M. arenaria found to be late in their 

 first year (Brousseau 1979). 



Of the 313 clams that were indistinguishable as to 

 sex, only 28 were < 25 mm in length, therefore we 

 cannot attribute this lack of discernable sex to im- 

 maturity. Furthermore, clams of indeterminate sex 

 were seen only during the fall and winter months 

 (September-March) when most clams were found to 

 be in the inactive stage. During the period of March- 

 September or spring-fall when the active, ripe, par- 

 tially spawned, and spent stages were well 

 represented, all clams could easily be determined to 

 be male or female. The difference between inactive 



male and female gonads is obvious and was seen in 

 many clams, yet many clams which were larger than 

 25 mm in length and should have been sexually 

 mature showed no signs of sexually distinguishable 

 tissue at all. No evidence of even small oocytes or 

 atypical spermatogenesis was seen in these clams. 

 For the sake of simplicity, these clams were placed in 

 the inactive stage. Perhaps this condition was a kind 

 of "gonadal exhaustion" due to the prolonged spawn- 

 ing period. 



The four study populations were dominated by 

 clams ranging from 40 to 75 mm in length (P^ig. 2). 

 This size range corresponds to the 1.5 to 4.0 year 

 classes determined by Brousseau (1979) for M. 

 arenaria from Gloucester, MA. While total corres- 

 pondence in growth rates between Massachusetts 



410 



