Detalle de: Settlement of mussels Mytilus galloprovincialis on an exposed rocky shore in Ria de Vigo, NW Spain

The mussel farming industry of the Galician re· gion (NW Spain) requires that 60 to 70% of its seed supply is taken from rocky shore areas. However there are almost no quantitative data for a recruitme nt and settlement pattern. In the Ria de Vigo a continuous settlement throughout the year with a major settlement season fr om May to September was fo und, reflecting the presence of spawning mussels through· out the year and the occurrence of a maJor spawning period during the spring. The observed settlement pattern indicates the direct settlement of larvae from the plankton onto the adult beds and an immigration of mussels previously settled on other substrates. This pattern could be a response to the ecological and environmental conditions that occurred on the Galician rocky shores, but could also be a differential charac· teristic between Mytilus edulis and M. galloprovincialis.