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Volume 45 - Suppl. 1 - 2010
Article

 


Age, growth and natural mortality of southern blue whiting, Micromesistius australis in the southeast Pacific Ocean

Mario Aguayo1, Javier Chong2 e Ignacio Payá3


1Instituto de Investigación Pesquera, Casilla 350, Talcahuano, Chile
2Universidad Católica de la Santísima Concepción, Casilla 297, Concepción, Chile
3Instituto de Fomento Pesquero, Casilla 8-V, Valparaíso, Chile

 

E-mail: jvchong@ucsc.cl

 

A study of age, growth and natural mortality of southern blue whiting, Micromesistius australis, was conducted using samples collected at latitudes from 46ºS to 56ºS, between 1991 and 1995. The age determination was made by reading annual growth increments in sagitta otoliths. The lengths at different ages were estimated using corrected backcalculated lengths. The annual formation of one hyaline and opaque ring was determined by the analysis of the otolith margin. In the study of growth in length, the traditional models of von Bertalanffy (VBT), the generalized (VBG), and the Gompertz (GOMP) were used. The parameter estimations were performed using a nonlinear function, and maximum likelihood, for each sex and for both sexes pooled together. Based on the coefficient of determination, the sum of the squared residuals and the Akaike criterion (AIC), the most representative model of growth was the traditional von Bertalanffy. The comparison of growth parameters between the sexes by the Hotelling T2 test and the reason of least squares, indicate a significantly higher growth for females. The growth parameters estimated for Micromesistius australis in the southeastern Pacific are different from those recorded for the southwest Atlantic and New Zealand, as they belong to different stocks. The instantaneous coefficient of natural mortality (M) was estimated by empirical methods that consider the close relationship between M and the growth parameters. The estimated values are lower than those reported in previous studies.

 

Key words: Merlucciidae, otolith, Chilean coast

 

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