to 8 times what would be expected on a good oyster growing bottom. 

 Mortality rates frcm 5 to 10 per cent are usual on natural oyster 

 reefs. It should be noted that these conditions prevailed in the 

 absence of any water whatsoever flowing into the area from the 

 Bonnet Carre Spillway or from brealcs in the Mississippi River 

 levee system. 



Four of the metal wire trays containing from 100 to 400 oysters 

 were placed at Stations Nos, 13, 17, 18 and 19 (Fig. 2). These 

 stations are on a line running roughly north and south, and ex- 

 tending across the ten mile western edge of Mississippi Sound. 

 This line is adjacent to the western limits of successful oyster 

 operations in the past. The majority of the oyster population was 

 lost in this area in the flood of 1945. The oysters placed in the 

 trays were dredged from the natural reef at Grand Island, Station 

 17, They were less than market size, ranging from 1 up to 3 inches 

 in length, and in very poor condition. It was felt, however, that 

 being native to the region, these oysters would provide a better 

 index as to what was happening on the reef during the period of 

 observation than if casters in good condition from another area 

 had been utilized. It should be noted too, that they were the 

 survivors of an abnoimally high mortality then in progress and 

 might perhaps have been more resistant to the adverse hydrographic 

 conditions, 



A second series of four trays was placed in Lake Mechant at 

 this time. These trays extended on a north-south line along the 

 eastern edge of the lake at Stations 20,21,22, and 23 (Fig. 3). The 

 middle locations are where the greatest mortalities occurred in 

 1945 in this lake. Station 23 was only partially affected by the 

 fresh water. Station 20 is located at that point where most of the 

 fresh water enters the lake and the bottom is too soft for oyster 

 culture. The trays contained from 100 to 200 oysters which were 

 dredged by a commercial boat from leased beds on the west side of 

 the lake. The oysters from the reefs in Lake Mechant, while larger 

 than those used in the trays in Mississippi Sound were stunted in 

 appearance and ranged from 1 to 3 1/2 inches in length. They were 

 in only fair condition and showed a recent mortality of slightly 

 less than 4 per cent. This is within the range found on good 

 oyster producing reefs. 



The salinities in the lake at this time were low, from 3 

 to 5.6 ppm, but the fact that the oysters were feeding and had 

 slight amounts of new shell growth indicated that the hydrographic 

 conditions were, on the average, suitable for maintaining the oyster 

 population. 



10 



