32 



U. S. BUREAU OF EISHERIES. 



sources of supply. It was a serious misfortune that Dr. Field died 

 shortly after completing and reporting upon his laboratory in- 

 Testigations. 



THE OYSTER. 



INVESTIGATIONS OF OYSTER CULTURE. 



The investigation of oyster problems of Great South Bay and 

 Long Island Sound was continued according to the general plan of 

 the year before. The work was begun by Dr. E. P. Churchill, as- 

 sisted by J. S. Gutsell, but Dr. Churchill left the service in August 

 and thereafter Mr. Gutsell continued it alone. Quantitative collec- 

 tions and studies were made with the aid of the pumping equipment 

 and selective screens developed by the Bureau investigators. 



At Great South Bay the plan comprised chiefly an intensive study 

 of the distribution, life, and setting of the oyster larvae. At fixed 

 stations located over a considerable area of the best oyster grounds 

 in the bay quantitative collections were made as in 1919. In that 

 year it had been found that certain of these stations were almost uni- 

 formly superior to others in their yield of larvse, and that the set 

 at these stations was correspondingly more abundant. The work in 

 1920 was planned to check up and enlarge on this evidence, to see if 

 the general distribution of larvae was much the same year after year. 

 Addition to our knowledge in other aspects was, of course, to be in- 

 cluded. 



Unfortunately the season was a poor one. Oyster larvae until 

 after mid- July occurred scatteringly, at best in small numbers. The 

 conditions indicated a very light set indeed. The one station which 

 showed decided superiority was not located over oyster beds and 

 offered no opportunity of determining a set. A return visit with 

 inadequate apparatus late in August showed young oyster larvae in 

 apparently fair abundance and indicated an unusually late spawning 

 and a possible late set. 



In accordance with the scarcity of larvae, a very light set was 

 found in the fall; and corresponding apparently to the late spawn- 

 ing, a set was found in the spring which had not attained sufficient 

 size in the fall to be noticeable. In general these sets were so light 

 as to be commercial only to the extent of having sufficient value to 

 repay shifting. 



Thus support was given the hypothesis that a relation can be 

 found between the observable abundance of larvae and the amount 

 of set, and that consequently a scarcity of larvae indicates that the 

 great expense of " shelling " should be avoided. 



In Long Island Sound, where the oysters spawn later than in 

 Great South Bay, the work was curtailed by the reduced personnel 

 and was limited chiefly to the region between Milford and Bridge- 

 port. Collecting was poor indeed except for a time in August, 

 when moderate numbers of larvae were obtained, particularly about 

 Bridgeport. Something of a set was later reported there. Thus in the 

 Sound, as in Great South Bay, there was little opportunity that season 

 to obtain other than negative evidence as to the relation of the occur- 

 rence of oyster larvae and the abundance and location of set. 



