These observations indicate that there is nothing inherent in 

 this stock of oysters to prevent normal growth, nor are the oysters 

 infected with microscopic parasites which are markedly deleterious. 

 In the period February to July these oysters were characterized by 

 their excellent growth, development of a better shape, and improve- 

 ment in the quality of the meat. In the absence of conflicting 

 evidence, it is my opinion that the lack of gro;rth in Mississippi 

 Sound was due to the freshness of the water. 



MORTALITY 



The preliminary survey of the Mississippi Sound oysters areas 

 affected by the 1945 flood showed, in the summer of 1948, that while 

 there had been good annual sets of oysters there had been no survival 

 of commercial importance. The hurricane of September, 1947 caused 

 considerable mortality on some of the bars. In other areeis having 

 high mortalities this storm could not have been the direct cause. 

 Local oystermen felt that the soft mud deposited by the floods, when 

 stirred up by storms, was perhaps instrumental in causing the annual 

 deaths of the small oysters by suffocating them. 



Survey of these bars in the first week of December, 1948 showed 

 that a fair proportion of the 1947 spat had survived and that the 

 mortality of the 1948 spat was less than 10 per cent. At this time 

 salinities on the bars averaged 5 to 6,5 ppm. During December, how- 

 ever, precipitation in the region was quite general and resulted in 

 a decline in the salinity. 



Experiments were designed to test the relative importance of 

 decreased salinity and turbidity in causing the oyster mortalities. 

 Metal wire trays which could contain up to 400 oysters were obtained 

 through the cooperation of the Department of V/ild Life and Fisheries 

 of the State of Louisiana. These cages permitted the placing of the 

 oysters so that part woixld lie on the bottom in the mud and the re- 

 mainder could be suspended six inches above the bottom. The weight 

 of the trays prevented their being moved by wave action. Conversely, 

 in some locations indiere the bottom was soft, the weight of the cage 

 caused it to sink into the mud so as to nearly cover the oysters in 

 the bottom layer. 



During the first two weeks in February a comprehensive survey 

 was made of the natural reefs and bottoms in western Mississippi 

 Sound and Lake Mechant, At this time the salinities in Mississippi 

 Sound were less than 1 ppm or entirely fresh. The water was muddy 

 and had other characteristics of river water. All of the oyster 

 grounds examined showed high mortality rates, ranging from 1 1/2 



