Estimación de abundancia y biomasa del cangrejo dorado (Chaceon chilensis), en el archipiélago de Juan Fernández, Chile

Abstract

The fishery-biology aspects of the Juan Fernandez golden crab ( Chaceon chilensis), and first estimates of the abundance and biomass of this resource distributed in the marine substrate surrounding Robinson Crusoe and Santa Clara islands are given. Information was obtained from samples taken within an experimental fishing survey for this crustacean, between 175 to 600 m depth, from March to June 1997. The theoretical area of influence methodology was used to estimate the abundance and biomass. Due to the degree of uncertainty of the variables employed, some parameters were sensibilized in order to obtain a range of estimates, along with its most likely value. Results indicate that the fishery of this resource is characterized by its catch mainly composed by males (97,8%), in the different types of traps used as well as in the whole bathymetric range surveyed. Specimens' length were between 84 and 147 mm of cephalothoraxic length. Maximum and minimum observed total weights were 250 and 1410 g respectively. The mean weight of a specimen (male) was 863 g. First most likely estimate of the golden crab available biomass, having sensibilized the area of influence of the trap, was determined to be 995,3 tons, that is a mean density of 2,9 individual/ 1000 m 2 and a maximum sustainable yield (MSY) of 75 tons. In the worst of the estimates scenery a MSY of 19 tons was obtained, and in the most optimistic scenery it reached 168 tons.