EFFECT OF MESH SIZE ON GROWTH AND SURVIVAL OF CULTURED MUSSELS (MYTILUS PLATENSIS D'ORB.) IN FRENCH NETTINGS

Abstract

Studies were performed on mussels (Mytilus platensis d'Orb.) cultured using the french netting technique at the Nuevo Gulf (42° 46' S, 65° 02' W), Chubut, Argentina. The effect of the mesh size of the external net tube on growth and survival of the individuáis wasstudied. Two size groups (seed group: average length = 24.0 mm; half-grown group: average length = 45.9 mm) and three mesh sizes (44.1 mm; 54.7 mm and 79.0 mm) were used. Results referred to the seed group show that growth and survival are not affected by mesh size. The proportion of mussels with low length increment and the proportion of individuáis retained by the net in the seed group are similar for all mesh sizes. For the half-grown group, the final average length using the smaller mesh size is significantly lower than in the other mesh sizes; significant differences there are no between the other two mesh sizes. The proportion of mussels with low growth in length and the number of individuáis retained inside the net are higher when the smaller mesh size is used whereas the number of lost mussels increase with increasing mesh size.