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Latin american journal of aquatic research

On-line version ISSN 0718-560X

Abstract

WIFF, Rodrigo; QUIROZ, J.C; OJEDA, Vilma  and  BARRIENTOS, Mauricio A. Estimation of natural mortality and uncertainty in pink cusk-eel (Genypterus blacodes Schneider, 1801) in southern Chile. Lat. Am. J. Aquat. Res. [online]. 2011, vol.39, n.2, pp.316-326. ISSN 0718-560X.

Pink cusk-eel (Genypterus blacodes) is a demersal fish of high economic importance for the multi-species and multi-fleet fishery operating off far-southern Chile (41°28'-57°00'S). Since the early 1990s, the existence of a single stock was assumed for purposes of stock assessments. However, several attributes related with life history and demography led to the designation, as of 2005, of two administrative stocks of this species, a northern-austral stock stock (41°28'-47°00S) and a southern-austral stock (47°00-57°00S). The division of these stocks has produced a demand for updating life history parameters, including natural mortality (M). In the present work, we used empirical methods to estimate M for pink cusk-eel by zone and sex. The uncertainty in M was incorporated through Monte Carlo resampling considering two sources of error: one from the life history parameters that feed the empirical models and the other from the coefficients that define them. The average M obtained by the different methods showed important differences between sexes for a given zone and between combined sexes between the different fishing zones. The M for individuals from the northern-austral zone was higher than that for those from the southern-austral zone. The coefficients of variation by method were highly dependent on the type of error incorporated. Pauly's (1980) method seems to be the most appropriate for pink cuskeel, providing M values for the combined sexes of 0.27 year-1 (IC: 0.130.47) for the northern-austral zone and 0.23 year-1 (IC: 0.11-0.40) for the southern-austral zone.

Keywords : Genypterus blacodes; natural mortality; demersal fishery; life history; demography; southern Chile.

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