Vertical distribution of hake Merluccius hubbsi in spawning aggregations in north patagonian waters of the SWA

EHRLICH, M.; MACCHI, G. J.; MADIROLAS , A.; MACHINANDIARENA, L.

Vigo

Conferencia; Fish Reproduction and Fisheries Conference; 2011

Instituto Investigaciones Marinas (CSIC)

Argentine hake (Merluccius hubbsi) inhabit waters of the Southwest Atlantic Ocean between 22 º and 55 º S, at depth ranging from 50 to 500 m. This species represents the most important fish resource of the Argentine Sea. The landings were 135143 t in 2010 representing 315051 dollars. Two stocks have been identified in the Argentine shelf, the northern stock between 34º and 41º S and the southern one between 41º and 55º S. As the southern stock is the most abundant, a lot of cruises were carried out by INIDEP regarding biomass evaluation, reproductive condition and offspring distribution. During cruises carried out in December 1996 and 1998 in the main spawning place of the southern stock a series of bottom and middwater trawls were realized during a cycle of 24 hours in about 70 m depth to observe vertical migration during spawning activity. In each haul hydroacustical data was recorded and a sample of ovaries was taken for maturity stages determination by histological analysis. The results showed that hake males and females were on bottom during the day time but at night, the spawning females were mainly near the bottom and the males ascended to upper layers, 30 m, and returned to the bottom in the next morning. This movement may be associated with the reproductive behaviour of hake.