The edible mussel (Mytilus edulis)

The mussel is one of the commonest bivalve molluscs around the Irish coast but quantity and quality vary greatly from place to place. Ideal conditions for the natural or farmed production of mussels are as follows:- (i) Sheltered bays or inlets; (ii) Firm shingly substrata; (iii) Good food supplies in the water; (iv) Absence of parasites and predators. Mussels on exposed shores subject to excessive water movement are usually slow growing and of poor quality. In other areas, although there is shelter from the action of wave and weather, the bottom may consist of soft mud or sand, neither of which is suitable for the settlement, survival and growth of mussels. Similarly areas may have the necessary shelter and firm substrata for the attachment of mussels, but, because the water does not produce an adequate supply of food material, the mussels do not flourish. Even in areas where there is shelter, firm substrata and plenty of feeding there may be many predators (e.g. crabs, starfish etc.) or parasites (e.g. redworm (Mytilicola intestinalis) and pea-crabs) which often render mussels unsuitable for marketing. Because of these limitations, it is not surprising that many areas of our coast produce mussels which are of poor quality. At present the five centres at which good quality mussels are produced are (a) Carlingford Lough (b) Dundalk Bay (c) River Boyne estuary (d) Wexford Harbour (e) Castlemaine Harbour (Cromane), Co Kerry