Seasonal variation in the length structure and reproductive condition of the jumbo squid Dosidicus gigas (d'Orbigny, 1835) off central-south Chile

Abstract

In the area off central-south Chile (34-40°S), a new period of high abundance of Dosidicus gigas has occurred since 2001. The seasonal changes in length structure and reproductive condition of D. gigas in oceanic and coastal waters are described for the period July 2003 to February 2004. The length structure varied significantly between seasons and zones. In the austral winter, medium-sized, maturing individuals were found in oceanic waters while large-sized mature males and maturing females were present in the coastal zone. In the austral spring, maturing medium-sized and large-sized individuals were observed in the oceanic zone. In contrast, two groups of individuals were observed in the coastal zone: one consisting of small and immature individuals, and one consisting of medium-sized maturing specimens. In the austral summer, only the oceanic zone was sampled, and samples contained small immature and maturing medium-sized individuals. We postulate that the spatial and temporal changes in length structure and reproductive condition of D. gigas off central-south Chile are probably due to the existence of a migratory strategy of the species in the study area.