Age and growth of the sparids Diplodus vulgaris, D-sargus and D-annularis in adult populations and the differences in their juvenile growth patterns in the north-western Mediterranean Sea

Age and growth patterns of adults of three common species of sparids, Diplodus vulgaris, D. sargus and D. annularis from the north-western Mediterranean Sea are analyzed. Length-at-age values are estimated from otoliths and growth patterns are well described by the von Bertalanffy growth equation. The sampled length interval ranged from 8-40, 28 and 20 cm for D. sargus, D. vulgaris and D. annularis, respectively. The estimates of t(0) for D. vulgaris and D. sargus, -0.67 and -0.74 respectively, indicate that the growth of these species during the first months of life do not adhere to the von Bertalanffy model. In contrast, for D. annularis the estimation of the origin of the von Bertalanffy model is close to zero (t(0) = -0.03), suggesting that this species is faithful to this growth model from the beginning of settlement. The variations from juveniles to adults in the growth pattern are explained by the permanence or the variations of the habitat of each of the species throughout their life. (C) 1997 Elsevier Science B.V.