Summer mortality of the blue mussel in eastern Canada: spatial, temporal, stock and age variation

Abstract

Survival of juvenile and adult blue mussels Mytilus edulis from several stocks was estimated at 3 sites in Prince Edward Island, Canada, from June 1987 to October 1988. In general, there was little evidence of spatial variability; the survival curves for a stock of a given age were similar across locations within a site and across sites. There were, however, significant differences in survival between years, stocks, and age groups. The cumulative survival was 0.77 for the period June to September 1987, as compared to 0.85 for the same period in 1988. Of the 3 groups which exhibited poor survival (0.59 to 0.72) in 1987, only one showed a similarly poor performance (0.66) in 1988. Overall, stock accounted for 28% of the variation in cumulative survival, whereas the contribution of the other main effects was negligible. Interaction terms which included Year, Stock, and Age accounted for 42% of the variance in mortality, suggesting a mutual dependence of these variables. Survival during the cold water months (October to May) was extremely high (> 0.95) for all groups.