GEOGRAPHICAL PATTERNS IN GROWTH ESTIMATES OF THE SCALLOP ZYGOCHLAMYS PATAGONICA, WITH EMPHASIS ON URUGUAYAN WATERS.

Growth parameters of the scallop Zygochlamys patagonica were estimated in Uruguayan waters of the southwestern Atlantic Ocean. Data used to estimate growth were collected at latitudes 35°50'S (northern end of the geographical distribution of the species) and 36°40'S (southern end of Uruguayan waters). Scallop ages were estimated by counting external growth rings on the left-hand valves. The von Bertalanffy function (VBGF) successfully explained some 93% (36°40'S) and 84% (35°50'S) of the variance. A likelihood ratio test indicated that scallops grew significantly faster at latitude 36°40'S than at latitude 35°50'S, confirming previous results showing large scale variation in density and individual muscle weight. Between-latitude differences were mainly ascribed to variations in the parameter t[sub0], which in turn could be explained by differences in observed lengths-at-age at earlier ages, notably age 1. Information on growth parameters of Z. patagonica, extracted from published sources over a wide latitudinal range (35°50'S-54°30'S), showed that asymptotic height H[sub∞] and the index of growth performance φ′ were inversely correlated with latitude, decreasing from north to south. The growth parameter estimates provided in this study ate consistent with the pattern. Management implications of these findings ate discussed, placing special emphasis on the applicability of spatially explicit management tools. [ABSTRACT FROM AUTHOR]