1129 



Loosanoff, Victor L. 1972. 



Research requirements for development of molluscan farming in the United 

 States. In Progress in Fishery and Food Science. Remedios W. Moore (edj . 

 Univ. Washington Pub. Fish., New Ser. 5, Seattle: 165-179. 



This review article discusses Mercenaria mercenaria, among other species, 

 under such headings as improvement of rearing methods for larvae and 

 juveniles, selective breeding, diseases and their control, enemies and 

 their control, contents and possible therapeutic qualities of meats, 

 utilization of thermal . effluents, purification and detoxification, improving 

 farming methods, and revision of laws. The paper contains no new data, but 

 it does introduce ideas and suggestions for further attention. The author 

 concluded that shellfish culture in the U.S. is still in a relatively 

 primitive stage. - J.L.M. 



1130 



Loosanoff, V. L. 1973. 



Urgent problems of molluskan farming. World. Maricult. Soc. , Proc. 4th. Ann. 

 Workshop: 341-352. 



The paper does not deal specifically with Mercenaria mercenaria, but problems 

 discussed are common to all species. Needed are methods to purify mollusks 

 that have become toxic from feeding on toxic plankton, better understanding 

 of the physiology of nutrition and development, and broad use of specifically 

 prepared foods, studies of epizootics and methods of their control, radical 

 changes in laws respecting mariculture, and training of future mariculturists. 

 Although mariculture is often referred to as an ancient art that has been 

 practiced for over 2,000 yrs, it has made virtually no progress in that time. 

 Principal constraints on molluscan farming, until recently, were from limited 

 budgets. - J.L.M. 



1131 



Loosanoff, V. L.,and H. C. Davis. 1949. 



The spawning of quahaugs in winter and culture of their larvae in the 

 laboratory. Convention addresses, Natl. Shellf. Assn. 1949: 58-66. 



Active and rapid gametogenesis begins in Mercenaria (Venus) mercenaria soon 

 after the completion of spawning, and by the end of October active spermatozoa 

 can be found in virtually all follicles of males. Thus, except for a brief 

 post-spawning period, spawning can be completed at all seasons. Ova develop 

 similarly. Clams are conditioned by raising temp slowly or immediately to 

 about 20°C. Under the latter conditions clams were brought from near 0°C to 

 spawning in 8 days. Conditioned clams are induced to spawn by raising the 

 temp to 32° to 34°C. Some groups spawned at temps as low as 20.6°C. Clams 

 provided spawn for 5 or 6 weeks before most were spent. Temp was more 

 important than stimulation by addition of sperm or eggs. The egg measures 

 about 70 u in diameter, and differs from eggs of many other lamellibranchs 

 because it is surrounded by a thick gelatinous envelope the diameter of 

 which varies between 163 and 170 \x. The larva enters the trochophore stage 

 about 12 hrs after fertilization. By this stage the gelatinous envelope is 

 gone. A shell covers the animal within 24 to 36 hrs after fertilization, 

 and in another 8 to 12 hrs the veliger or straight hinge stage is reached. 

 This veliger swims with a well-developed velum. By the 6th day it is in early 

 umbo stage, in 8 days in medium umbo stage, and in 10 days in late umbo stage, 

 and in 12 days some of the mature, ready-to-set larvae may be as large as 

 227 to 210 u . Just prior to this stage the larvae begin to undergo very 

 prominent changes. The velum begins to disappear and some functions are 

 taken over by a foot. The ciliated foot first aids in swimming, but 

 gradually is used to glide over the bottom and to crawl. Many larvae reached 

 setting stage in about 12 days. Length of the prodissoconch is 210 to 225 y, 

 or sometimes up to 240 p. Larvae are not too selective in their food. On 

 almost a pure culture of Chlorella, however, they grew more slowly and 

 suffered heavier mortality. Cultivation of clam larvae to setting is 

 relatively easy. - J.L.M. 



316 



