In February a supply of oysters selected at random from the 

 shallow water reef at Grand Island, Station 17, was brought to 

 Pensacola along with samples from Lake Mechant, The oysters from 

 the latter area were commercially dredged near, our Station 23. 

 They were fairly small oysters but averaged twice the size of the 

 Mississippi Sound samples. Length and breadth measurements were 

 recorded for a sample of each of these groups and the oysters were 

 placed in wire trays at a depth of 5 feet, approximately the depth 

 of the bars from which they had been taken. These oysters were left 

 undisturbed until the first of June, vten size measurements were again 

 recorded, as well as mortalities. At this time a third tray of oysters 

 was added which had just been measured and transplanted from Station 

 17 to the laboratory. At the end of June the oysters were examined 

 again. For comparative purposes, a tray of Florida oysters, native 

 to this area, was maintained in the same location throughout the 

 period of observation* 



Table 1 summarizes the growth of these oysters, expressed as 

 increase in length In millimeters, following their transplantation 

 from the waters of Lake Mechant and Mississippi Sound to Pensacola, 

 Florida. 



The most significant point is that in the period February 

 7 - May 25 the average length of oysters remaining on the reef at 

 Grand Island increased from 31 to 33 mms., or, practically not at 

 all. The same stock of oysters moved to Florida for this period of 

 time increased an average of 16 mm. or 51 per cent in length. The 

 native Florida oysters increased 42 per cent during this period, 

 while the Lake Mechant oysters increased but 16 per cent. The small 

 increase for the latter group may be attributed to their initial 

 larger average size. In general, the growth rate of oysters decreases 

 as they become larger. The growth rates during the month of June were 

 relatively low in the first three samples but in the new sample from 

 Grand Island it wss quite high. This was probably due to the stimulus 

 of moving them to a new location. 



Changes in the width of the oysters moved to Florida was dlsi>ropor- 

 tionately greater than length changes with the result that by the end 

 of May, all samples, including the native controls had broadened to 

 a more desirably shaped oyster. This is an expected result of separat- 

 ing clustered oysters and permitting them to grow unhampered. 



During the course of these observations, water temperatures In 

 Florida closely paralleled those in Mississippi Sound. However, the 

 salinity in Florida averaged 18 ppm whereas in Mississippi Sound it 

 avereged less than 5 ppm and for much of the period was close to 

 zero, i. e. , fresh water. 



