22 V. S. BUREAU OF FISHERIES. 



of the deeper water of Long Island Sound, where low temperatures 

 Jiad prevailed and a failure of set occurred. 



In Great South Bay the spawning season extended from about 

 June 5 to July 17, the heaviest spawning occurring July 2 to 6, and 

 the greatest abundance of larvae being found from July 7 to 11. 

 Spawning began about the time the water temperature reached 70° 

 y., and proceeded briskly while it ranged from 70 to 76°, but slowed 

 down or ceased when the temperature fell to 70 and 68°. When the 

 water temperature rose to 75° and above, about July 2 to 6, the bulk 

 of the spawn was thrown out within the course of two or three days. 

 The approximate length of the free-swimming period was 12 to 14 

 days. Considerable mortality of the free-swimming larvae followed 

 a sudden lowering of water temperature or the severe agitation of 

 the water by storms. 



The investigation served to throw considerable light on the proper 

 time of planting cultch and the best location of plants for catching 

 a set. 



OYSTER INVESTIGATIONS IN LITTLE EGG HARBOR, N. J. 



Dr. T. C. Nelson, assistant biologist of the New Jersey Agricultural 

 Experiment Station, completed during 1919 a six months' study of 

 the food and feeding of oysters. While this work, carried on at 

 Edge Cove, Tuckerton, N. J., was primarily State work,, yet, since 

 its beginning and continuity were made possible by the cooperation 

 of this Bureau, a summarized account of the results attained is not 

 out of place in this connection. 



Studies of the food of oysters were conducted from a floating lab- 

 oratory anchored directly over the oysters, making it possible to keep 

 a continuous record of the temperature, density, and rate of flow of 

 water, parallel with examination of the food content of oysters. 



The results of the microscopic analyses indicate that minute ani- 

 mals may play an important part in the oyster's nutrition. Copepods, 

 nauplius larvae, ostracods, gastropod and bivalve veligers, round 

 worms, rotifers, and protozoa were found in great numbers. As a 

 typical case, the contents of the stomach of one oyster showed over 

 4,000 nauplius larvae and 60 large copepods, besides many protozoans. 

 That these crustaceans are digested was shown by the large number 

 of skeletal parts found in the stomach and intestine. 



To study the rate of growth, 1,000 oyster's were tagged, weighed, 

 measured, and put out on a fixed platform 1 foot above the bottom. 

 In 130 days these oysters grew in some instances as much as 3 centi- 

 meters (1.2 inches), while the increase in weight for oysters 1 and 2 

 years old was from 40 to 60 per cent. The duration of feeding in the 

 oyster was determined by levers led from the shell of an oyster lying 

 on the bottom to an electrical recording instrument (chimograph) 

 above. The oyster, under natural conditions, continued to feed from 

 19 to 20 hours out of every 24. 



One result of the investigation of the oyster's food has been the 

 demonstration of the large part played by organisms growing on the 

 oyster's shell. On the shell of one oyster 5 inches long were found 

 diatoms in number computed to be over 56,000,000. Oysters covered 

 with external growths may be partly independent of the actual food 

 content of the water flowing over them. 



