BIOLOGIYA MORYA, 2016, Vol. 42, No. 2, pp. 87-92

Age distribution models for fish in catches

© 2016 V. V. Sukhanov

A.V. Zhirmunsky Institute of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok 690041;
Far Eastern Federal University, Vladivostok 690950

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The models describing age distributions of fish in catches are discussed. On a logarithmic scale of the Y-axis, the right (descending) part of these curves can be straight or can have an upward or downward concavity, as well as a sharp bend in the middle. These properties of the curves can be explained by variations in the intensity of mortality between different age groups or by demographic variations in the super-population systems. Illustrations of catch-by-age curves are provided.

Key words: logistic ogival curve, gamma-distribution, selective catch, uneven-aged maturation, mortality coefficient.