A COMPARATIVE STUDY OF THE HARD CLAM GONAD DEVELOPMENTAL CYCLE

¹ University of Delaware, College of Marine Studies, Field Station, Lewes, Delaware 19958

1. This study has shown that hard clam reproductive cycles in Delaware Bay are in phase and that spawning activity during 1971-1973 was of sufficient intensity to provide ample larval stocks.

2. The gonad developmental patterns for clams in Delaware are intermediate between those for Long Island and North Carolina. The data provide supporting evidence that different physiological races exist in the three areas compared. A further test on the validity of physiological races could be determined by studying the developmental patterns of Long Island and North Carolina clams held experimentally in Delaware Bay.

3. Environmental factors attribute to subtle differences in reproductive physiology as evidenced by the different mechanisms of regeneration and development between Delaware Bay and Henlopen hard clam females.

The authors wish to thank Dr. Melbourne R. Carriker, Dr. R. W. Menzel, Dr. L. Watling, Mr. Hugh Porter for critical review of the manuscript, and Dr. Jonathan Taylor and Ms. Ann Taylor who provided photographic support for the project. This study was supported in part by the National Marine Fisheries Service, P. L. 88-309, Project No. 3-135R.