PS 9-85 - High fisheries yields caused by life histories under bycatch persistence in transient time scales

Background/Question/Methods

The establishment of marine reserves plays an important role in improving fisheries yields of strong stock species while maintaining the persistence of bycatch weak stock species. However, the prevalent equilibrium analyses prevent our understandings in transient dynamics in fisheries adaptive management. By incorporating age structure, we develop a two-species model including both target and bycatch species to compare the yields of target species under different harvesting strategies.

Results/Conclusions

With practical applications to the West Coast groundfish fishery in the USA, our
research suggests that strategies with reserves can have higher fisheries yields than strategies without
reserves under the persistence of bycatch if target species have old ages at maturity and low adult
survivorships. In addition, if fisheries yields are measured by weight, fisheries management has multiple choices
over short time scales, which is contrary to the conclusions when yields are measured by numbers. The generality
of applying our theoretical frameworks to fisheries management is tested with hypothetical parameters. Our
work can be used to choose suitable measurement metrics and design more precise optimal fisheries strategies for
given natural systems with specific life histories.