Spawning aggregations of Merluccius hubbsi, in Patagonian waters: evidence for a single stock?

Abstract

From 1971, a small scale bottom trawl fishery has developed in the San Matías Gulf (41°–42° S; 64°–65°W) of the Argentinean Sea, targeting the hake ( Merluccius hubbsi Marini). The dynamics of a spawning aggregation of hake in the gulf were analyzed based on changes in sex ratio and the proportions of different stages of sexual maturity. It was concluded that the northern part of the gulf is the main spawning zone. While males are concentrated there, mature females come to the area, spawn, and then move back to the west zone. The presence of a spawning aggregation and the occurrence of all stages of the life cycle in the San Matśas Gulf, suggests that the hake population in the Gulf constitutes a stock unit separate from the continental shelf stocks. Further support for this hypothesis is provided by the oceanographic characteristics of the Gulf.