Production, reproductive effort, reproductive value and reproductive cost in a population of the blue mussel Mytilus edulis from a subarctic environment

The standing crop of mussels MytiIus edulis from Bellevue. Newfoundland, is similar to that of the densest beds in warmer waters, but population production is not as great. Production by individual mussels at Bellevue exceeds that in most populations for which appropriate data are available. Detailed comparison with a population in the Lynher estuary, southwest England, confirms previous conclusions, based on physiological measurements, that Lynher mussels experience greater stress than Bellevue mussels, despite the considerable temperature advantage enjoyed by the former. Expression of growth in terms of day-degrees suggests that there is no meaningful analysis based on temperature alone. Reproductive effort is high in M. edulis at Bellevue, reaching 0.94 in the oldest individuals. Residual reproductive value attains a maximum at 3 to 4 yr, after which ~t decreases rapidly.