131 



Baptist, John P. 1955. 



Burrowing ability of juvenile clams. U.S. Dept. Interior, Fish Wildl. Serv. , 

 Spec. Sci. Rept. — Fish. 140, 13 p. 



The paper deals with Mya arenaria. Meraenaria (Venus) meraenaria is not 

 mentioned. - M.W.S. and J.L.M. 



132 



Baptist, J. P., D. A. Wolfe, and D. R. Colby. 1976. 



Effects of chronic gamma radiation on the growth and survival of juvenile 

 clams (Meraenaria meraenaria) and scallops ( Argopeaten irradians) . Health 

 Physics 30(1) : 79-83. 



Lots of 30 clams each (mean length 10.8 mm) were exposed to 5 intensities 

 of gamma radiation for periods up to 14 months. Exposure rates ranged 

 downward from 37 rads/hr to a level slightly higher than background 

 radiation. Adverse effects on growth and survival occurred only at the 

 highest exposure rate. Growth slowed and then stopped at 12 weeks, but 

 this probably was caused by inadequate food. Survival was 100% up to the 

 4th month, then the group exposed to highest rate began to show some 

 mortality. - J.L.M. 



133 



Bardach, John E., John H. Ryther, and William 0. McLarney. 1972. 



Aquaculture. The Farming and Husbandry of Freshwater and Marine Organisms. 

 Wiley-Interscience, New York, 868 p. 



Chapter 37: 743-756. Culture of clams and cockles. - Clam culture is second 

 only to oyster culture in antiquity among aquatic invertebrates, but it has 

 never been as widespread or highly developed, perhaps because clams are 

 abundant and easy to harvest in nature. Clam culture in Japan is described. 

 North American oyster culture is quite primitive as compared with Japan, but 

 the U.S. has taken the lead in clam culture. Meraenaria meraenaria is by far 

 the most popular. The basic hatchery procedure is the "Milford method", with 

 which, by controlling water temp, it is possible to spawn hard clams any day 

 of the year. Quahogs are more tolerant of varying temp than oysters but not 

 as tolerant of low salinity. Swimming larvae can withstand salinities as low 

 as 15°/oo but successful hatching of eggs and development to straight-hinge 

 stage requires at least 22°/°°. Optimal salinity for development of quahog 

 eggs in Long Island Sound is 27°/°o. Larvae are similarly plastic with 

 respect to pH, but a pH range of 7-8.5 is required for normal development. 

 Larvae develop normally at temps from 18 to 30°C, but optimum is near the 

 upper limit. At 30°C setting may occur 7 days after hatching, at 24°C 10 

 days may be required. Dissolved 02 concentration does not seem to be too 

 critical, but well-oxygenated water should be provided. Pumping and re- 

 spiratory rates are directly related to O2 demand. The lower the 02 the 

 harder the clam must pump, which reduces the energy available for growth. 

 At Milford, quahogs fed Saenedesmus ohliquus in dried form grew nearly as 

 well as those fed live food. At 10°C hard clam larvae will ingest, but not 

 digest and assimilate, algae. At 15°C algae with thin cell walls only would 

 be digested. At 25°C quahog larvae can digest most algae. Seed clams 

 sometimes are planted in the natural environment as small as 3 mm long, but 

 it is preferable to hold them until at least 12.5 mm to reduce predation. 

 At present the center of the quahog industry in the U.S. is N.Y., where 

 growth to marketable size takes 5 to 8 yrs . The industry may shift to the 

 south to take advantage of faster growth. The world's first commercial clam 

 hatchery was established in Va. Hybridization of M. meraenaria with its 

 southern counterpart M. oampeahiensis has potential for quahog culture in the 

 south. Southern quahog grows faster but does not keep as well. Hybrids 

 appear to be intermediate in keeping quality out of water. Seed clams from 

 Milford, Conn, transplanted to Alligator Harbor, Fla. reached marketable size 

 in 2 yrs. Somewhat larger seed (33-44 mm) were market size in 8-10 months. 

 In Fla. salinity must be at least 25°/°° and bottom firm. If water is too 

 shallow, high summer temp may cause mortality at low tide. Density of 



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