The Reproductive Biology of the Softshell Clam,Mya arenaria, in Ireland, and the Possible Impacts of Climate Variability

Abstract

Little is known about the biology of the softshell clam in Europe, despite it being identified as a potential species to culture for food in the future. Monthly samples of the softshell clam,Mya arenaria, were collected intertidally from Co. Wexford, Ireland, over a period of sixteen months. The mean weight of sampled individuals was74±4.9 g and mean length was8.2±0.2 cm. Histological examination revealed a female-to-male ratio of 1 : 1.15. In 2010,M. arenariaat this site matured over the summer months, with both sexes either ripe or spawning by August. A single spawning event was recorded in 2010, completed by November. Two unusually cold winters, followed by a warmer-than-average spring, appear to have affectedM. arenariagametogenesis in this area, potentially affecting the time of spawning, fertilisation success, and recruitment of this species. No hermaphrodites were observed in the samples collected, nor were any pathogens observed. Timing of development and spawning is compared with the coasts of eastern North America and with other European coasts.