Modeling the responses of the coupled social-ecological systems of the northern Gulf of California to anthropogenic and natural perturbations

Background/Question/Methods

Given the extent and magnitude of natural and anthropogenic disturbances influencing ocean ecosystems, there is increasing interest in more integrated, ecosystem-based approaches to managing human interactions with coastal and marine ecosystems. Key elements of marine ecosystem-based management include: a) understanding connections among social and ecological systems and b) developing analytical approaches to inform the necessary trade-offs between ecosystem services and human activities. To address these needs, we investigate the impacts of multiple fishing sectors on the marine ecosystem and dependent human community in the northern Gulf of California by using an ecological-economic modeling approach. To represent the ecological domain, we initially focus on the spotted rose snapper (Lutjanus guttatus), an economically important species. This fish occupies diverse nearshore habitats, exhibiting ontogenetic migration during its life cycle (e.g., from nearshore estuarine and mangrove areas to coastal reefs), and thus is impacted by multiple fishing sectors, including the nearshore artisanal fleet, the sports fishery, and the industrial shrimp fleet.

Results/Conclusions

We model the snapper population as comprised of two distinct subpopulations representing juvenile and adult fish, which are connected via recruitment and juvenile migration. Juvenile fish are impacted by fishing mortality caused by shrimp bycatch, while adult fish are subject to artisanal and sports-fishing. Economic returns to the human community are driven by the catch in artisanal fisheries and the number of tourists who engage in sports fisheries, and these variables are in turn impacted by fish abundance. Using a combination of analytic and simulation approaches, we investigate the linkages between the ecosystem and the human community. We find that tighter coupling between the ecological and social systems leads to more variable fish abundance and returns to the human community. There is a threshold at which the system switches from one dominated by artisanal fishing to one dominated by sports-fishing. We then explore how changes in exploitation and climate variability impact the persistence of the coupled social and ecological systems in the northern Gulf. We anticipate that these results will be of great interest to other scientists engaged in empirical and theoretical efforts to understand the dynamics and drivers of social-ecological systems as well as to practitioners engaged in marine management and conservation efforts in the Gulf of California and elsewhere.