1655 



Shaw, William N. 1972. 



Aquaculture of mollusks along the west coast of the United States. 

 Bull. Am. Malacol. Union, Inc. 37: 23-24. 



Commercial clam culture is very limited on the Pacific coast. Most clam 

 landings are by recreational fishermen. Possibilities are recognized for 

 culture of soft clam, razor clam, common littleneck and Japanese littleneck. 

 Mercenaria mercenaria is not mentioned. - J.L.M. 



1656 



Shaw, William N. 1974. 



Aquaculture of molluscs along the United States Atlantic and Gulf coasts. 

 NOAA Tech. Rept. NMFS Circ 388: 57-65. 



American oyster, hard clam and bay scallop are discussed. Mercenaria 

 mercenaria is distributed along the Atlantic coast and Gulf of Mexico. Peak 

 production was 21 million lbs (of meats) in 1950, dropped to 14.2 million in 

 1955, and since has remained fairly stable at between 13.3 and 15.8 million. 

 N.Y. is the leading producer. Va., N.J., N.Y., Mass., and R.I. together 

 accounted for 91% of U.S. hard clam landings in 1970. In N.Y. the center of 

 the resource is the south shore of Long Island in sheltered bays like Great 

 South Bay. Gears include tongs, rakes, dredges, hoes, grabs, and by hand. 

 In 1967 in N.Y. dredges, tongs, and rakes made the catch. The hydraulic 

 escalator dredge was recently introduced (on private grounds only) and does 

 little damage to clams or beds. This gear is also used in Chincoteague Bay, 

 Md. The fishery appears to be in excellent condition although there is 

 concern about water pollution. Of 450,000 acres of potential shellfish 

 producing bottoms in N.Y. 156,892 acres are closed. Depuration is feasible 

 and would cost about $1.76/bu. The most intensive efforts at propagation 

 have been made on Cape Cod and Long Island. Clams are artificially spawned 

 and reared in hatcheries to the seed stage, then transplanted to growing 

 areas. Heavy losses from predation are a problem. In Va. a method has been 

 developed to protect young clams from predation by spreading crushed oyster 

 shell, crushed stone, or pea gravel on the bed and planting clams of match- 

 head size at 25 to 50 clams/ft 2 . Survival as high as 80% has been obtained 

 by this method. One of the largest clam hatcheries is in N.C. Approximately 

 4 million larvae are produced per week, and reared to metamorphosis in about 

 2 wks, then placed in shallow trays mounted vertically in banks of 10 trays. 

 The set is held in trays for 8 wks, then transferred to running sea water in 

 concrete raceways. Seed clams measure 1 to 2 cm at 14 wks. When they reach 

 2.5 cm they are sold as seed clams or planted. In the U.S. many companies 

 have tried molluscan aquaculture and failed. Coastal waters are used 

 primarily for navigation and recreation, and access for aquaculture is 

 limited. Costs are high, and profits will be possible only with high-priced 

 species. In most states legal regimes favorable to development of aauaculture 

 do not exist. Pollution, or the threat of it, also is a problem. It is hoped 

 that these problems can be solved. - J.L.M. 



1657 



Sheldon, R. W. 1967. 



Relationship between shell-weight and age in certain molluscs. J. Fish. Res. 

 Bd. Canada 24(5): 1165-1171. 



Mercenaria mercenaria was among seven species examined. It was assumed that 

 annual growth is detectable by rings or annuli on the external surface of the 

 valves, and age was determined in this way. A linear relationship of shell 

 weight to age appeared to exist between ages of 2 and 8 years. Annual in- 

 crements (estimated from fig. 2) were approximately 15 grams. Older clams 

 were not available. The samples were obtained from Southampton Water on the 

 south coast of England. - J.L.M. 



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