Age and Growth of Yellownose, Dipturus chilensis (Guichenot, 1848), in the Southwestern Atlantic (34°- 55°S)

ZAVATTERI ANABELA ; HOZBOR NATALIA; BELLEGGIA MAURO

Minneapolis

Congreso; Joint Meeting of Ichthyologists and Herpetologists; 2011

American Society of Ichthyologist and Herpertologists

The yellownose Dipturus chilensis inhabits the southeastern Pacific and southwesternAtlantic Ocean. It is extensively exploited in both targeted fisheries and as by catch inthe southwestern Atlantic. This study contributes to the knowledge of the age andgrowth of D. chilensis providing biological information that is essential for developingsustainable fisheries management strategies. Age and growth was studied based onvertebral analysis of 415 specimens collected on the Argentinean continental shelf (34oS- 55o S). Males specimens ranged from 24 to110 cm (n=203), while females specimensranged from 24 to 115 (n=211). Sectioned vertebrates were stained with cobalt chloride.The marginal increment analysis (MIA) supported the hypothesis that D. chilensisproduces one growth band pair each year, which ends during autumn. Maximumestimated age was 21 and 25 years for males and females, respectively. The vonBertalanffy growth function was selected based on the best fit to the age-length data tomales (L∞=114.32 cm; k=0.10 years-1; t0=4.95 years) and females (L∞= 149.05 cm; k=0.07years1; t0=-8.11 years). Significant difference was detected between male and femalesgrowth parameters. Females reach larger size than males. These results indicate that D. chilensis is a long-lived and slow growing species. Therefore, it is particularly vulnerableto over-exploitation by fisheries.