Seasonal aspects of sarcomatous neoplasia in Mya arenaria (soft-shell clam) from Long Island Sound

Mya arenaria were collected monthly for 2.5 years from three populations in Long Island Sound. Histopathological examination revealed that 6.1% of the clams from Stonington, Connecticut, 12.9% of the clams from the Saugatuck River, Westport, Connecticut, and 12.7% of those from Old Mill Beach, Westport, also in Connecticut, had sarcomatous neoplasms. This is the first documented account of the occurrence of clam neoplasm in populations from this geographic area. Peak prevalences of 45, 59, and 60%, respectively, were found in clams from the three study sites. The prevalence of neoplasms in clams collected from three epizootic areas showed a pronounced seasonal pattern, with the highest incidences occurring in the late fall-winter of each year studied. The regular, seasonal occurrence of neoplasia in field populations does not support the hypothesis that pollution alone is the cause of the disorder.