Offshore spawning of the Argentine hake (Merluccius hubbsi) Patagonian stock

The spatial variation of the spawning shoals of M. hubbsi in Patagonia during its reproductive peak (January) between 2001 and 2008 was analyzed. In 2001 and 2004 spawning of hake in the north-patagonian area was concentrated inshore between 50 m and 80 m depths, in coincidence with a bottom thermal front (9° 14° C). Since 2005 an expansion of spawning into deeper waters (near the 100 m isobath), where bottom temperature ranged between 6° and 8° C, was observed. This offshore group was characterized by a high proportion of females (0.58 – 0.78), larger (modes 53 – 62 cm TL) than those of the coastal region (modes 40 – 45 cm TL). The relative fecundity and oocyte dry weight values were lower in the offshore spawning area than those obtained for the inshore reproductive ground. This observation could indicate that the offshore group corresponds to hake females at the end of spawning in migration to deeper waters.