Traditional calculation of catch age composition estimate requires that the age-length data and random length frecuency be sampled from the same population, in other case an age-length key is capable of providing biased estimates of age distribution. By using the iteration algorithm is possible to overcome this limitation.
The catch age composition for Dissostichus eleginoides was obteined with the aplication of a single age-length key to all monthly length distribution using the nonlinear model (Hoenig and Heisey, 1987). We found a catch age distribution pattern wich is not significatly different from the one obteined by use of traditional method
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Abstract:
With samples originated in the Chilean longline fishery of Dissostichus eleginoides of subarea 48.3 (N=7848) after Sparre (1990) the natural mortality was calculated . The Von Bertalanffy parameters obtained independently by three authors were used and considering as variables: fishing site, fishing depth and hook type.
It was determined that there was no significative differences, in M value, in the considered cases with the different growing parameters, with the exception of the case of fishing sites. By other hand, when comparing the different mean values of M for the different variables , it was found that there were significative differences between fishing sites and curve hooks N° 14 and straight hooks N° 22.
The general mean value of M calculated for the 44 analyzed situations was 0.14 ± 0.03, being the range between 0.0623 - 0.2727.
