Áreas potenciales de descarte de merluza para la actividad de la flota comercial argentina
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To improve the quality of the resource assessment it is necessary to estimate discards and quantify them applying an adequate methodology. The purpose of this work is to detect areas where the activity of the commercial fleet coincides with zones of high concentration of juveniles because they are potential discard areas. To establish possible seasonal and/or interannual variations, length distribution data derived from hake research surveys carried out on board of INIDEP vessels during the 1986-1993 period were analyzed. Samples were grouped per statistical rectangle on the basis of catch weighted average and mean, variance, skewness and kurtosis were calculated. The resulting parameters were subjected to a cluster analysis using the Euclidean distance and Ward index. Besides, juveniles percentage (individuals below 35 cm total lenght) and sex proportion per statistical rectangle and season were calculated. To analyze the dynamics of the commercial fleet, catch and effort data for the same period were used. Results indicate that the areas of highest concentrations of juveniles are located north of 37° S and southwards between 43° S and 47° S, from the coast to 62° W, both at 50-150 m depth. The strong presence of the argentine commercial fleet in the southern area, intensified as of 1990, led to consider it a potential discard area. North of 37° S the fleet had scarce presence during the period analyzed. Neither area showed seasonal and/or interannual variations, so they were considered representative of the 1986-1993 period to estimate discards quantitatively.