ECOLOGY OF BUZZARDS BAY: An Estuarine Profile 47 



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Fig. 4.4. Scallops Aequipectin irradians Photo by D 

 Goehringer. 



along the eastern shore, and the headwaters of the 

 bay. 



Adult bay scallops are highly mobile, propelling 

 themselves through the water by expelling water 

 through the rapid contraction of their shells by their 

 adductor muscle. This muscle is highly prized for its 

 delicate flavor and provides the main edible portion 

 of the scallop. Bay scallops grow quickly and rarely 

 live more than 2 years. Scallops have only one 

 spawning season and environmental conditions can 

 cause unpredictable sets (Lee 1980; Capuzzo et 

 al. 1982). The combination of a short life span and 

 limited spawning season is partially responsible for 

 the large fluctuations in clean populations that drive 

 the large annual variations in catch. Spawning gen- 

 erally occurs during early summer when water tem- 

 peratures approach the annual maximum (20-24° 

 C) and are coincident with phytoplankton blooms 

 (Sastry 1966, 1968). Although bay scallops are 

 generally most abundant in shallow embayments, 

 they are also found, occasionally in large numbers, 

 at depths of 4. 5- 12 m in Buzzards Bay (Capuzzo 

 1 984). Studies of bay scallop gonads taken from 

 offshore stations in Buzzards Bay (9 m depth) 

 showed offshore populations spawned earlier and 



over longer periods than inshore populations (e.g.. 

 Wings Cove, 2-m depth). Although catches are less 

 predictable in the offshore areas, the scallops ap- 

 pear to have 20-50% more muscle weight than 

 specimens collected inshore (Capuzzo etal. 1982). 

 Scallops are filter feeders and as juveniles are 

 sedentary, often attaching themselves by byssal 

 threads to eelgrass (Zostera marina) blades above 

 the sediment surface. The impacts of nutrient pollu- 

 tion — such as increasing epiphyte growth or tur- 

 bidity in the water column, which decreases light 

 availability — can have serious consequences for 

 eelgrass beds, hence scallop populations, by elimi- 

 nating an important substrate for the early growth 

 of juveniles. Eelgrass blight or wasting disease, re- 

 sponsible for the loss of large expanses of eelgrass 

 beds in various areas along the North Atlantic coast 

 (1931-32), has indirectly been identified as the 

 cause of subsequent declines in scallop populations 

 in these regions. The presence of toxic pollutants 

 such as heavy metals may also affect scallop popu- 

 lations. The scallop fishery in Acushnet River and 

 Clarks Cove has declined in recent years, possibly 

 as a result of exposure to the high levels of copper 

 in New Bedford Inner Harbor and Outer Harbor 

 sediments. Copper in the water column has been 

 shown to reduce growth in these shellfish 

 (Sindermann 1979; Davis 1989). Whatever the 

 cause, scallop harvests have been low for the past 

 decade. 



Crassostrea virginica, the common oyster, is 

 not as abundant in Buzzards Bay as other harvested 

 bivalves. The entire eastern shore of the bay (Figs. 

 1.4,3.1, and Table 3.1), the Agawam, Westport, 

 and Weweantic rivers. Wings Cove, and parts of 

 Sippican Harbor (in Marion) all support oyster 

 beds. After going through initial juvenile stages, 

 young oysters (known as "spat") require a hard 

 substrate upon which to settle and grow and are 

 often found on rocks, pilings, or frequently other 

 oysters. As in the case of other bivalve mollusks, 

 they are subject to a variety of natural predators 

 (e.g., crabs, birds, sea stars, and oyster drills). 

 Oyster harvesting is not presently a large commer- 

 cial industry around Buzzards Bay, but evidence of 

 past oyster harvests exists in shell middens, or shell 



