Survival and growth of local and transplanted blue mussels (Mytilus trossulus, Lamark)

Consumer demand for fish and shellfish has led to an increase in aquatic species movement for aquaculture purposes. One potential drawback to the successful transplantation of animals for aquaculture is unpredictable performance due to local adaptation effects. This study used a common environment experiment to examine the potential for local adaptation in Mytilus trossulus (Lamark) on the east coast of Vancouver Island, British Columbia (BC). Newly settled mussels were collected from two sites, Chemainus and Quadra Island (approximately 150 km apart), reared in cages at the Quadra collection site, and mortality and shell length were monitored. Mussels were cage‐reared for 384 days with an overall survival of 59% (Quadra) and 39% (Chemainus). The Quadra mussels were initially smaller (5.07 mm) than the Chemainus mussels (5.90 mm), but the two were similar at the end of the experiment (23.5 and 23.6 mm). Transplanted mussels had a significantly higher mortality over the course of the experiment, primarily due to a severe episode in the early summer, and had significantly lower relative growth rates at three of 11 measurement dates. Overall, the local mussels performed better than the transplanted mussels. This study demonstrates the potential for local adaptation effects between populations of mussels separated by only a relatively small geographic distance.