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 46º and 56º 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 T 2 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.

Traveling around Cape Horn: Otolith chemistry reveals a mixed stock of Patagonian hoki with separate Atlantic and Pacific spawning grounds

“…Both species are targeted by commercial fisheries, with annual catches of 473,900 and 259,800 t respectively in 1999 (FAO, 2008). Patagonian hoki stocks in Chile have strongly declined over recent years (Chong et al, 2007) while abundances in the South Atlantic seem to be increasing (Wöhler et al, 2007).…”

Edad, crecimiento y mortalidad natural de merluza de tres aletas, Micromesistius australis en el Océano Pacífico suroriental

“…El análisis siguiente consistió en determinar, el número de anillos hialinos (oscuros) y opacos (blanquecinos), registrar las medidas del radio del otolito (Ro) y el radio de cada anillo hialino (Rn), y determinar el tipo de borde. Previo a la medición de cada radio fue necesario pulir la cara interna de cada otolito con un esmeril de grano fino, a fin de visualizar el foco (Chong et al 2007). …”