Estimación de edad, crecimiento y mortalidad natural de la merluza de cola, Macruronus magellanicus Lönnberg, 1907 (Macruronidae, Gadiformes) en el Océano Pacífico Suroriental

Abstract

Age, growth and natural mortality in Chilean hoki, Macruronus magellanicus, are estimated using samples of saggital otoliths from specimens caught from 1991 to 1996 between 46° and 56° S. The age determination was done by reading of annual growth ring in otoliths. The lengths at different ages were obtained by back calculation and also to actual ages. The validation of the annual formation of otoliths increment was established by the regularity of the deposition of the hyaline and opaque rings in the edge of the otoliths and the marginal increment analysis. This allowed the determination of the formation of an annual hyaline (annulus) in July and an opaque ring in January. The growth was determined following the von Bertalanffy model and the growth parameters were assessed separately for each sex, using a nonlinear adjustment model. The growth parameters between sexes were compared with the T2 test of Hotelling and the minimum square ratio of Chen et al. (1992). The results indicate that growth was significantly greater in females than in males. The results obtained here are consistent with previous records for the same species from other regions of the Eastern Pacific, the Western Atlantic, as well as with the congeneric species M. novaezelandiae, from the coasts of Australia and New Zealand. The instantaneous coefficient of natural mortality (M) was estimated with empirical methods and catch-curve analysis.