Abundance, Growth, and Production Estimation of the Blue Mussel Mytilus edulis on Moored Navigation Buoys in the Estuary and Northwestern Gulf of St. Lawrence

Production of Mytilus edulis was estimated from measurements of recruitment, growth, and abundances. The study is based on (1) yearly samplings carried out between 1975 and 1985 on 161 navigation buoys moored each year in the Estuary and Gulf of St. Lawrence and (2) monthly production estimates in a reference region in 1987. The relationships between production and maximum size, biomass, mean weight per individual, and abundance were calculated for this reference region. Maximum size and biomass were the parameters best reflecting production. Abundance and production estimates showed that the Gaspé Peninsula and the western North Shore zones were the most productive ones. The density-dependent mortality of individuals in crowded even-aged populations (self-thinning) was studied in the baie de Gaspé, the region showing the highest abundance and growth rate of Mytilus in the system. The slope of this relationship varied depending on initial density and age classes considered. These results, when compared with the theoretical value of the self-thinning model, suggest that the biomass observed on the buoys and the production estimates derived from them correspond to near-maximal values