Investigators: Susan Piacenza, Morgan DuBois, Paul Richards (NOAA SEFSC), Jennifer Lee (NOAA SERO)
Assessment of population status and likely impacts is essential for effective conservation and management of endangered long-lived highly migratory species. Here, we evaluate the likely status of the critically endangered Kemp’s ridley sea turtle (Lepidochelys kempii) in their primary habitat of the Gulf of Mexico under different management scenarios. In recent decades, the species showed signs of recovery, but the nesting trend has been more volatile since Deepwater Horizon in 2010 and continues to face a number of threats. The spatial distribution of Kemp’s ridleys overlaps with many anthropogenic impacts, such as shrimp trawling and longlining, in addition to others, with most threat overlap occurring in the northern Gulf coastal zone from Texas to northwest Florida. We developed a spatially explicit management strategy evaluation (MSE) to evaluate trade-offs in management options, such as bycatch reduction from trawl fisheries, and dynamic spatial closures. For the operating model we use an agent-based model (ABM) that includes demographic stochasticity for key life history traits, such as age-at-maturity, breeding frequency, egg production, and annual survival rates, and environmental stochasticity in breeding frequency. Our spatial domain includes variability in benthic productivity that can influence foraging movements and includes migratory patterns related to foraging and nesting. The ABM also includes fishing vessels that track benthic productivity and depth, and have the probability to encounter and bycatch turtles. Management options evaluated include reducing bycatch by lowering fishing mortality, and dynamic spatial closures. The MSE analysis includes model validation and sensitivity analysis, and management scenarios in relation to abundance and population trend. This MSE permits managers to make conservation decisions based on trade-offs in sea turtle recovery and impacts to fisheries, dynamic spatial closures, and bycatch mitigation.
Assessment of population status and likely impacts is essential for effective conservation and management of endangered long-lived highly migratory species. Here, we evaluate the likely status of the critically endangered Kemp’s ridley sea turtle (Lepidochelys kempii) in their primary habitat of the Gulf of Mexico under different management scenarios. In recent decades, the species showed signs of recovery, but the nesting trend has been more volatile since Deepwater Horizon in 2010 and continues to face a number of threats. The spatial distribution of Kemp’s ridleys overlaps with many anthropogenic impacts, such as shrimp trawling and longlining, in addition to others, with most threat overlap occurring in the northern Gulf coastal zone from Texas to northwest Florida. We developed a spatially explicit management strategy evaluation (MSE) to evaluate trade-offs in management options, such as bycatch reduction from trawl fisheries, and dynamic spatial closures. For the operating model we use an agent-based model (ABM) that includes demographic stochasticity for key life history traits, such as age-at-maturity, breeding frequency, egg production, and annual survival rates, and environmental stochasticity in breeding frequency. Our spatial domain includes variability in benthic productivity that can influence foraging movements and includes migratory patterns related to foraging and nesting. The ABM also includes fishing vessels that track benthic productivity and depth, and have the probability to encounter and bycatch turtles. Management options evaluated include reducing bycatch by lowering fishing mortality, and dynamic spatial closures. The MSE analysis includes model validation and sensitivity analysis, and management scenarios in relation to abundance and population trend. This MSE permits managers to make conservation decisions based on trade-offs in sea turtle recovery and impacts to fisheries, dynamic spatial closures, and bycatch mitigation.