Impacts of Large Male-Selective Harvesting on Reproduction: Illustration with Large Decapod Crustacean Resources

To signal a need for caution for present large male-selective harvesting practices, negative impacts of the large male-selective harvesting on reproductive output in large decapod crustacean resources are introduced with emphasis on my own work with spiny king crab Paralithodes brevipes, coconut crab Birgus latro, and the stone crab Hapalogaster dentata. The large male-selective harvestings for several large decapod crustaceans have changed their population demographic structure by decreasing mean male size and skewing sex ratio towards females. By several field and laboratory experiments, the change of population demographic structure was anticipated to decrease female reproductive success in the resources (i.e. reproductive output of the harvested populations) through a decrease in sperm availability for females because of male size-dependent reproductive potentials and slow sperm recovery rate. Furthermore, reproductive output and stability of the large male-selective harvested resources were also anticipated to decline by a decrease in mate availability for females, attributing to combination of female mate choice for larger males with negative effects of female delayed mating and/or maternal influences. To establish the optimal management practices, the details of the mating system and reproductive ecology of each targeted species should be investigated.