Reproductive features of two Patagonian toothfish (Dissostichus eleginoides) aggregations in the Southwest Atlantic Ocean

PÁJARO, M.; MACCHI, G. J.; MARTINEZ, P.; WOHLER, O

Lisboa

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

NAFO

Spatial distribution of maturity stages and estimates of length at maturity for two aggregations of Patagonian toothfish (Dissostichus eleginoides) in the Southwest Atlantic Ocean were analyzed. Samples (n=42,821) were collected from longline commercial fishery between 2003 and 2006. The northern group occurs over a wide latitudinal range from 36°S to 50°S while the southern group inhabits the area from 52°S to 60°S. Annual analysis of the maturity stage composition of the northern group showed that 24% of fish were juveniles, 54% were reproductively active individuals and less than 0.1% were males in spawning condition. The lack of running females suggested that spawning of D. eleginoides does not take place in the north area. With respect to the southern group, only 13% of fish were juveniles, 60% were reproductively active individuals and 4% were in spawning stage. Monthly analysis of maturity stage composition for this group suggested that main spawning activity occurs from June to October. On the other hand, spatial distribution of maturity stages showed that 85% of spawning individuals were observed in waters deeper than 1000 m. Length at maturity (L50%) for the northern and southern group was 84.7 and 81.7 cm total length, respectively; statistical differences between groups were observed (p0.28) in length at maturity was observed between fish inhabiting deeper waters (deeper than 1000 m depth) and inshore waters. Other aspects as reproductive behavior and environmental features in relation with the population structure of D. eleginoides are discussed.