BROUSSEAU and BAGLIVO: FIELD POPULATIONS OF AfTA ARENARIA 



Table 2.— Densities per 0.1 m^ of Mya arenaria in size-classes 

 2-50 mm in the Westporl and 2-60 mm in the Stonington popula- 

 tions in 1985 and 1986. 



period (10 months) obtained by dividing the number 

 of 1-yr-olds alive in the summer 1986 by the esti- 

 mated cohort size in the previous year were 0.0283 

 and 0.5869 for the Westport and Stonington popu- 

 lations, respectively. 



Size-specific survival rates of adult clams {>1 year) 

 at both sites are shown in Tables 3 and 4. These 

 represent empirical estimates from mark and recap- 

 ture studies with survival adjustments in the larger 

 classes made according to Equations (2) and (3). 

 Statistical comparison of the survival distributions 

 of adult clams, however, was limited to those re- 

 covered live or recovered showing some growth. At 

 the Westport site survival was constant across the 

 10 mm size classes: 20-29 through 50-59 and 60 -i- . 

 At Stonington, however, the size-specific survival 

 for classes 30-39 through 70-79 and 80 -i- increased 

 slightly with size (P < 0.05, x^ test). The probability 



18 



30 



35 



Wp 1 



46 



52 



57 



63 



68 



74 



79 



17 



16 



O 16 



LU 

 U- 



O 15 



O 



« • » 



« * « « 4 • * 

 * • * * 



* * V ■« • • 



• * * • * 



•3 ;• 



2* *»2* *♦ **? 

 * * 2 • * 



* « « 



* ««* 22*** 



• • 2 • * * 



* 2 * * 



• •*223* • 



15 



13 



27 



33 



38 



44 



49 



55 



6C 



66 



7 1 



82 



SHELL LENGTH (mm) 



Figure 2.— Continued— the Stonington (STN) and Westport (WPl) populations. 



571 



