Spatial distribution and growth of the common mussel Mytilus edulis L. in the archipelago of SW-Finland, northern Baltic Sea

Abundance, biomass, size distribution and growth of the common mussel, Mytilus edulis L. along a transect extending through the SW archipelago of Finland, northern Baltic Sea are described here for the first time. The parameters studied were found to vary according to environmental gradients extending from the inner to the outer archipelago. The lowest densities and biomass were found in the innermost archipelago. Most of the populations here consisted of small individuals between 4 to 6 mm (antero-posterior length), while in the middle and outer archipelago areas modal size was approximately twice as large. The average growth rate of mussels in the middle archipelago was higher than in all other areas. Very slow growing, or “dwarf” mussels were found in all areas studied, but these were most common in the outer archipelago.