A SEX-STRUCTURED DELAYED RECRUITMENT MODEL

A delay-difference model for a sex-structured population with delayed recruitment is presented. Constant-effort harvesting is introduced for examining the model's sensitivity to harvesting. Linear analyses abou t the steady states are performed under various parameter choices. The effects of the delay period, the survival parameter, and the harvesti ng effort on population stability are examined. It is shown that diffe rences in the male and female delays to recruitment can give rise to v ery different stability diagrams. Our analyses indicate, for example, that a population with equal male and female delays to recruitment is the most robust to recruitment failures. Possible forms that the male and female recruitment functions could take are suggested and evaluate d. Finally, the very encouraging result is obtained that maximum susta inable yield is attained at a stable steady-state population level.