versión On-line ISSN 0717-7178
GATICA, Claudio y CUBILLOS, Luis. Size-structured analysis of abundance changes in Merluccius gayi gayi between 1992 and 2000. Investig. mar. [online]. 2004, vol.32, n.1, pp. 71-87. ISSN 0717-7178. doi: 10.4067/S0717-71782004000100006.
The present situation of the Chilean hake (Merluccius gayi gayi) is analyzed for the period between 1992 and 2000 through a length-based stock assessment model. The advantages and disadvantages of the model are analyzed, which consist of a general model of population dynamics structured by age and sex, models for the observations of total annual catches, fishery and survey length composition, and abundance from hydroacoustic surveys. The estimation processs allow a simultaneouly estimation of the parameters through log-likelihood functions, penalties, constraints, and a priori information for some parameters. The stock indicators show a population in a period of high abundance and biomass, after a growing trend in the adult abundance of the stock from 1993 to 1998. This situation has been a consequence of higher recruitments occurring between 1993 and 1997. In 1998 and 1999 the recruitment was less abundant, ranging from 358 to 430 millions of individuals, while in 2000 it increases until 816 millions of recruits. This series of good recruitments in addition with moderates and lower exploitation rates would have generated the favorable increment in the total biomass of Chilean hake during the 1990s. Under this scenario, is opportune to know how we can improve the knowledge of the resource and their populational dynamics, by detecting sources of uncertainties and variability for the abundance and by examining processes that should be incorporated in the assessment tool. This model can be seen as an alternative tool that besides quantifying the abundance and biomass among other indicators, would allow to work on hypothesis of populational dynamics
Palabras clave : common hake; stock assessment; lenght composition; Chile.