GROWTH OF THE TROPICAL SCALLOP, EUVOLA (PECTEN) ZICZAC, IN BOTTOM ANDSUSPENDED CULTURE IN THE GOLFO DE CARIACO, VENEZUELA

We compared the growth of the scallop Euvola (Pecten) ziczac (L.) in t hree situations which potentially could be used for commercial culture , in cages maintained in suspension, in cages on the bottom and in cag es partly buried in a sediment bottom. The latter permitted the scallo ps to bury themselves as in their natural habitat. Throughout the 7-mo nth study, growth, as measured by shell length and muscle mass, was by far superior for scallops in the partly buried cages. Possible explan ations for this are (1) that the scallops are stressed by enclosures w hich prevent them from burying themselves and (2) that organic materia l at the sediment/water interface is an important food resource and E. ziczac has better access to this when it buries itself flush with the bottom, The timing of gonadal growth and spawning varied markedly amo ng treatments. Some spawnings coincided with temperature increases but others did not. Differences between scallops in suspension compared t o those in bottom treatments suggested that reproduction is as much co ntrolled by conditions in the immediate environment of the scallops as by large-scale environmental factors, Survival was highest for the sc allops maintained in partly buried cages.