Indoor nursery cultivation of juvenile bivalve molluscs using diets of dried algae.
Juvenile bivalve molluscs (Tapes philippinarum, Crassostrea gigas and Ostrea edulis) were grown in 1000-litre recirculating seawater upwelling systems. Growth rate for Manila clam (Tapes philippinarum) with a dried (mixed) algae diet of Tetraselmis suecica and Cyclotella cryptica was only slightly lower than with a live (mixed) algae diet of T. suecica and Skeletonema costatum. Clams fed on a mixture of 90% dried T. suecica and 10% live S. costatum grew as well as with the live (mixed) diet. When live S. costatum was used in the diet mixture, the inclusion of C. cryptica in the dried component did not improve growth rate. T. philippinarum juveniles grown in the upwelling systems were transferred to the sea, molluscs previously fed on the 100% dried diet showed greater growth potential than those previously fed on the 100% live diet. Pacific and European oysters (Crassostrea gigas and Ostrea edulis) needed 30%-50% live S. costatum in diet mixtures with dried algae to support growth comparable to a mixed live algae diet. The cost of rearing juvenile bivalve molluscs in indoor nurseries in relation to the ration and diet fed is discussed.