FISHERY BULLETIN: VOL. 86, NO. 3 



Figure 1.— Map showing locations of the two study sites: Barn Island in Stonington, CT (A) and Saugatuck River in Westport, CT (B). 



tina altemijlora marsh. The substrate there is 

 coarser than at the Stonington site; 50% by weight 

 is >4 mm grain size diameter, much of that classi- 

 fiable as either cobble or boulder (Brousseau and 

 Baglivo 1987). Both study sites are closed to shellfish 

 harvesting to high levels of bacterial contamination. 

 Although annual salinity and temperature profiles 

 for the two sites are not available, monthly surface 

 and bottom salinity and temperature readings for 

 the period March 1979- June 1981 and October 

 1985-August 1986 are available for four sites in 

 western Long Island Sound: Norwalk, CT (lat. 

 41°02.5'N; long. 73°27.2'W), Bridgeport, CT Gat. 

 41°08.7'N; long 73°11.1'W), Stratford, CT (lat. 

 41°07.6'N; long. 73°07.6'W), and New Haven, CT 

 (lat. 41°14.4'N; 72°54.2'W)(Tettlebachetal., 1984; 

 Blogoslawski, pers. comm.^). All water sampling was 

 done at spring low tide in approximately 20 ft of 

 water. The annual average range of surface temper- 

 atures for the four sites was 0.5°-24.2°C. The 

 lowest surface temperature, 0.0 °C, was recorded at 

 the New Haven station in February 1980; the high- 

 est was 25.0°C recorded at the Stratford station in 

 August 1986. Annual average range of bottom 

 temperatures was 0.6°-23.4°C. Surface sahnities 

 ranged from 16.9 to 33.3°/oo with a low of 15.97oo 



reported for Stratford and a high of 35.77oo re- 

 corded at the Norwalk station. Mean bottom salin- 

 ities during that period ranged between 17.0 and 



34.4«/oo. 



Fecundity 



Oocyte production by female clams collected dur- 

 ing the summer spawning seasons of 1984 and 1985 

 was estimated using a histological technique (Brous- 

 seau 1976). One hundred twenty-five gravid females 

 from the Westport population and 123 from the 

 Stonington population were examined. Size-specific 

 fecundity rates were converted to age-specific rates 

 using age-size information for M. arenaria obtained 

 from analysis of internal shell growth bands (Brous- 

 seau and Baglivo 1987). Age-specific fecundity 

 estimates for x-yr-old clams, m^., were calculated 

 using the formula: 



Mx = 0.5 ^ Wj P(size-class i | x yr-old) 



(1) 



'W. Blogoslawski, Northwest Fisheries Center Milford Labora- 

 tory, National Marine Fisheries Service, NOAA, Roger Avenue, 

 Milford, CT 06460, pers. commun. March 1987. 



where m^ is the mean fecundity for size-class i, 

 P(size-class i \ x-yr-old) is the conditional probabil- 

 ity that an x-yr-old clam is in size-class i, and the 

 sum is taken over 10 mm size-classes i. The condi- 

 tional probabilities P (size-class i \ x-yr-old) were 

 derived empirically (see Appendix Tables 1, 2). Ten 

 millimeter size-classes were used because of sparse- 

 ness in the data. By convention, m^ represents the 



568 



