Alternative reproductive strategies of Ostrea puelchana

Abstract

Three reproductive strategies of Ostrea puelchana from the San Matias Gulf (Rio Negro, Argentina) are described and discussed. These relate to the degree of grouping shown by the oysters; i.e., (a) Carriage (this strategie is unique to the Ostreidae); (b) clusters and (c) isolation. Incidence of these strategies differed among three study sites (Banco Reparo, Las Grutas and Bajo Oliveira). Carriage incidence was maximal at Bajo Oliveira (69.4 % of the individuals), intermediate at Banco Reparo (49.7 %), and minimal at Las Grutas (19.7%), where clusters and isolated individuals predominate. Clusters constituted only a small fraction at Bajo Oliveira (1.1 %) and Banco Reparo (3.5%). The percentage of males larger than 50 mm was notedly lower at Banco Reparo (8.0 %) than at Las Grutas (39.3 %). The Las Grutas oysters associated in clusters have a higher percentage of males (57.9%) than at other locations and in any other type of association.