FISHERY BULLETIN: VOL. 86, NO. 3 



RESULTS 



Fecundity 



Fecundity of Mya arenaria increased with in- 

 creasing female body size (Fig. 2). Size-specific 

 fecundity schedules, however, differed at the two 

 study sites. Comparison of regression lines for 

 log(fecundity) vs. shell length by analysis of covari- 

 ance indicated that the relationships were signifi- 

 cantly different {P = 0.004). Size-specific oocyte pro- 

 duction in the Stonington clams was larger than in 

 clams from Westport. The smallest gravid females 

 observed were 34 and 27 mm in shell length in the 

 Stonington and Westport populations, respective- 

 ly. Age at first reproduction is 1 year in clams from 

 both sites. Sex ratios in both populations did not 

 differ significantly from 1:1 (Brousseau 1987a). 



Recruitment and Mortality 



Both temporal and spatial variations in annual 

 recruitment were observed during the study period. 

 A substantial settlement occurred at the Westport 

 site in 1985, as evidenced by the high densities of 

 2-20 mm clams present in late July of that year 

 (Table 2). In contrast, spat densities at the Stoning- 

 ton site were low in early August of 1985, when 

 settlement occurred. Nonetheless, persistence of the 

 1985 year class at Westport was poor, whereas ap- 

 proximately one-half of those set in the Stonington 

 population during that year were alive one year 

 later. The coarse substrate at the Westport site may 

 have aided attachment of the byssal stage juveniles, 

 resulting in the higher recruitment rate during the 

 summer of 1985. Direct estimates of M. arenaria 

 survivorship during the postsettlement to 1-yr 



1 7 



30 



35 



46 



52 



Stn 



57 



63 



68 

 - + + - 



79 



16 



D 



O 16 



LLI 



« « 



e « « 



• « 

 * « « 



a * « • * 

 * • * • * * « 

 * * « « 2 * 



3* »••««•« 

 »«*«*«« « «* 



' * 22 * • • 



2 • * • 



2 •2** 



O ,5 



o 



15 



13 



27 



33 



38 



- + + - 



49 



55 



60 



66 



82 



SHELL LENGTH (mm) 



Figure 2.— Log of fecundity versus shell length for Mya arenaria from 



570 



