Optimum Age-Specific Harvesting in a Nonlinear Population Model

The age-specific harvesting policy for maximizing equilibrium yield in a discrete-time, selfregenerating, age-structured population model is determined. The model assumes that survival of animals in their first year of life is density-dependent, while survival, growth and fecundity at other ages are density-independent. The optimal policy is of the 'two-age' type. Other forms of age-selective harvesting, which are practically more feasible, are discussed, and an example using data for Arcto-Norwegian cod is provided to demonstrate the possibility of increasing yields from fisheries by such methods.