An approach to estimate the natural mortality rate in fish stocks

Cubillos, L.A. (2003) An approach to estimate the natural mortality rate in fish stocks. Naga, Worldfish Center Quarterly, 26(1), pp. 17-19.

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Abstract

A simple approach is introduced to estimate the natural mortality rate (M) of fish stocks. The approach is based on the age at maximum cohort biomass, or critical length (L*) concept. The ratio of the critical length to the asymptotic length ( = L*/L8) is relatively constant in 141 fish stocks at 0.62 (CV = 21.4 per cent) and the relationship M = 3K(1- )/ is derived and could be used to estimate M, where K is the growth coefficient of the von Bertalanffy growth function. Average values of are given for the various Families of fish in order to estimate M based on closely related species.

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