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Zusammenfassung |
The authors simulated length-frequency distributions for 3-, 7-, and 13-age-class exploited populations (Peprilus triacanthus, Gadus morhua, Paralichthys dentatus, Pomatomus saltatrix ) to compare the performance of Shepherd's length composition analysis (SRLCA) and MULTIFAN in resolving the distributions to age frequencies. The length distributions were characterized by von Bertalanffy growth, variable recruitment, variable mortality, partial selectivity of fishing gear for the youngest age-groups, and a length-dependent trend in the standard deviation in length at age. Comparative performance of SRLCA and MULTIFAN was assessed quantitatively by using the Kolmogorov-Smirnov cumulative distribution test to compare calculated proportions at age with the simulated values. Shepherd's analysis provided a good return for the amount of computational resources invested, with limited subjective user input. In contrast, MULTIFAN offered a much more complex but powerful estimation technique, and performed consistently better than SRLCA in matching the simulated proportions at age. |
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