PROGRESS IN BIOLOGICAL INQUIRIES, 1932 125 



narcotizing solution can be used for several consecutive batches of 

 oysters. 



Oyster imrstigations in Florida — Three surveys were made by Dr. 

 Prvtherch of the oyster beds and condition of the industry in Apala- 

 chicola Bay and Choctawha tehee Bay on the west coast of Florida. 

 Examinations of 11 of the most important bars in the former locality 

 in January showed no evidence of depletion and an abundant supply 

 of seed and adult oysters. Overcrowding of oysters was evident on 

 most of the natural bars which should be corrected by transplanting 

 a certain proportion of the culled or undersized oysters to adjacent 

 firm bottoms where better conditions, for feeding and growth are 

 available. In the fall serious destruction of oysters was reported in 

 St. George Sound on the natural and planted beds in the vicinity of 

 Porters Bar. Studies made there in November showed that 50 to 75 

 percent of the oysters had been killed by a parasitic flatworm or so- 

 called "leech." From 1 to 4 flatworms were found in each affected 

 living oyster or in the empty shells of recently killed specimens. 

 Similar outbreaks of this parasite have occurred previously at Tampa, 

 Cedar Keys, and Indian River Inlet during dry warm seasons and 

 similar conditions were apparently responsible for the high mortality 

 of oysters in St. George Sound. 



A new and promising territory for the production and cultivation 

 of oysters was found in Choctawhatchee Bay. The recent formation 

 of a new inlet to the Gulf of Mexico has greatly increased the salinity 

 of the water and produced excellent conditions for oyster growth and 

 reproduction. Experimental plantings of seed oysters and shells will 

 be made here during the summer of 1933 to determine the most 

 practical measures for increasing the production of the natural beds 

 and the development of oyster culture on barren bottoms, 



PACIFIC COAST OYSTER STUDIES 



Oyster investigations in the State of Washington. — The experimental 

 study of the cultivation of Olympia oysters, begun in 1931, in coop- 

 eration with the Washington State Department of Fisheries and 

 Game, was continued during this year. 



An intensive study is being made of the spawning and setting of 

 larvae in the two most important oyster producing bays in the Ol3an- 

 pia region. For this purpose, wire bags filled with large shells were 

 planted twice a week in certain typical dikes. Each bag of shells 

 was allowed to remain in the water 7 days, when it was brought into 

 the laboratory and counts made of the number of spat which had 

 been caught. In Oyster Bay the setting season may be divided dis- 

 tinctly into two parts. The first setting period began on June 26, 

 reached its peak on July 5, and ended about July 25, at which time 

 a second setting period started. The peak of this period was reached 

 on August 25 and setting practically ceased by August 31. From 

 this time until the middle of October, periods of constantly decreas- 

 ing abundance of setting occurred. At the peak of the first set, 

 something over 6,000 spat per day per bag of shells were taken, while 

 at the peak of the second set, approximately 7,500 were caught. 

 Oyster grounds down the bay from the great mass of oyster beds 

 gave results entirely similar, except that the total set was only about 

 one fifth as great as that above described. 



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