GAMETOGENESIS IN THE OYSTER UNDER CONDITIONS OF DEPRESSED SALINITY

¹ Chesapeake Shellfish Investigations, Fish and Wildlife Service, U. S. Department of the Interior, Annapolis, Maryland

Histological examination of oyster gonads from an area naturally exposed to prolonged periods of fresh water, when compared to oyster gonads from an adjacent, unexposed area, showed:

1. Gametogenesis was inhibited in 90 per cent of the surviving population until salinity levels rose above 6 parts per thousand.

2. Following the salinity increase, oysters rapidly improved in condition but required from three to four months to attain the same final level of gonad activity as the unaffected group.

3. Marked variation and suppression of gonad activity in the exposed oysters is attributed to variations in food availability, rather than to direct inhibition of sexual activity by less saline water.

4. Sex ratios and extent of intersexuality in the population sampled, as well as details of the gametogenic cycle, agree for the most part with published observations on Ostrea virginica in other parts of its geographical range.