Fish Population Dynamic and Stock Assessment

4.2.3.3. Rikhter and Efanov’s formula

Rikhter and Efanov (1975) showed a close association between ‘M’ and ‘Tm 50%’, the age when 50% of the population is mature (also called the age of massive maturation)

M = 1.521 / (Tm 50% ^0.720) - 0.155 per year

‘Tm 50%’ is equal to the optimum age defined as the age at which the biomass of a cohort is maximal.