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Evaluation of three methods of bottom culture of the tropical scallop Euvola (Pecten) ziczac (L. 1758)

Abstract:

Three methods were used to study the growth and survival of juvenile Euvola ziczac (initial shell height of 40.4 mm SD = 4.2), and initial dry mass tissues of 0.35 g (SD = 0.01), which were set out at a density of 15 individuals m-2 on a sandy bottom at Turpialito in the Golfo de Cariaco, Venezuela. The first method was applied on an area of 3 x 5 m (15 m2) with minimum demarkation (0.20-m low walls) on the bottom, the second method was applied on 1 x 1 m corrals with 1-m high walls, and the third method on 1 x 1 x 1 m cages with bottom and top covers. Both treatments with high walls were conducted with 15 replicates. We could not quantify growth and survival in the first treatment, because the rate of escape was >80% month-1 (12 scallop m-2 month-1). In the corrals, the escape rate increased progressively from 4% (1 scallop m-2 month-1) to 36% (5 scallop m-2 month-1), suggesting that the swimming ability of Euvola ziczac increased with size from an initial 40.4 mm to final 69.7 mm in shell height obtained in this study. No scallops escaped from the cages, but survival was less than in the corrals. Our observations suggest that the most appropriate bottom culture method would be corrals with walls higher than 1 m.