The hydra effect in the dynamic model of age and sex structured exploited population

On the discrete-time model basis we study the influence of selective harvest on the dynamics of a population with age and sex structures. We consider three harvest strategies, when some part of a younger age class, or mature males, or mature females are removed. We show that the exploited sex and age-specific group equilibrium size (after reproduction) can increase with the increase of harvested individuals proportion; that is, the hydra effect is observed.