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Relation of RNA/DNA ratios to growth for the scallop Euvola (Pecten) ziczac in suspended culture

Abstract:

We examined the relation of RNA/DNA ratios to growth for three size groups of the tropical scallop Eurola ziczac maintained in suspended culture at 8, 21 and 34 m in depth in the Golfo de Cariaco, Venezuela. Various growth parameters indicated that production decreased with depth. This was more likely due to a decrease in seston quality with depth than to temperatures or seston abundance (which were similar at the various depths studied). The RNA/DNA ratio was correlated with the G-index of muscle growth for juveniles (r2 = 0.55). A much weaker correlation was observed for the maturing scallops (r2 = 0.18), probably because of the interaction between reproductive and somatic growth. In fully mature scallops, somatic growth was negligible and the RNA/DNA ratios appeared to be inversely related to the level of physiological stress of the scallops. Whereas RNA/DNA ratios are difficult to interpret for maturing E. ziczac, because an increased ratio can be due to either increased gonadal or somatic growth, they are useful in pbkp_redicting growth in juveniles and physiological stress in fully mature scallops.