Reproductive potential of the Argentine hake, Merluccius hubbsi, in Patagonian waters

MACCHI, G.J.; PÁJARO, M.

Lisboa

Simposio; Symposium Reproductive and Recruitment Processes of Exploited Marine Fish Stocks; 2007

NAFO

Batch fecundity, spawning frequency and size at maturity of the Argentine hake inhabiting the Patagonian waters, south of 41° S, were estimated by using samples collected during the spawning peak (January) in 2001, 2004, 2005 and 2006. Batch fecundity (BF) was fitted to a power function of total length (TL) and age, and to a linear function of ovary-free female weight, ranging from 100,000 (31 cm TL) to 2,900,000 (90 cm TL) hydrated oocytes. No significant differences (P>0.01) were observed between the coefficients of the relationship BF vs TL estimated for different years. Inter annual comparison of the relative fecundity showed similar results, with values ranging from 100 to 1000 hydrated oocytes per female gram (without ovaries). Spawning frequency, determined from the proportion of females with day-1 postovulatory follicles, was similar in January 2001 (0.15), 2005 (0.18) and 2006 (0.18), but lower in 2004 (0.08). At these frequencies, a female hake spawned once every 5 or 6 days in January 2001, 2005 and 2006, and every 12 days in January 2004. Argentine hake females reached sexual maturity at a higher size than males, but low variability between the values estimated for different years was observed. This variable ranged from 27.78 cm to 28.41 cm TL in males and from 33.21 cm to 34.44 cm TL in females. In conclusion, the reproductive variables analyzed showed low annual variation at the main spawning peak, independent of changes in Argentine hake abundance or local oceanographic conditions during the period considered.