Development of a dynamic management tool to aid in the bycatch reduction and recovery of the critically endangered Eastern Pacific leatherback turtle

The critically endangered Eastern Pacific leatherback turtle has declined by over 97% since the 1980s and is at risk of regional extinction. Leatherback turtles historically nested along Mexican and Central American nesting... [ view full abstract ]

The critically endangered Eastern Pacific leatherback turtle has declined by over 97% since the 1980s and is at risk of regional extinction. Leatherback turtles historically nested along Mexican and Central American nesting beaches. Impacts from fisheries bycatch and egg poaching are among the major reasons for their decline. Management of leatherback turtles and other highly migratory marine organisms requires an understanding of their year-round distributions to reduce fisheries bycatch both nearshore and offshore. In this study, we combined satellite telemetry data and fisheries observations of leatherback turtles to develop a habitat-based model of their distribution. In order to account for the complexities of the data set, a novel modeling approach was applied in this analysis. We used a Poisson generalized linear model in a continuous-time Markov chain (CTMC) model framework for the telemetry data to predict individual, post-nesting leatherback movement throughout the South Pacific based on environmental drivers, such as sea surface temperature. Population-level estimates of leatherback movement were obtained with a Bayesian approach. Fisheries observations were incorporated using a point process model to estimate density under varying environmental conditions for these predominantly juvenile leatherbacks. Monthly, near-real time predictions of leatherback movement throughout the South Pacific are then estimated with these parameters and the most recent satellite-derived environmental information. This tool will help to inform managers, fishers and other stakeholders how to anticipate and prevent fisheries interactions, which is vital for ensuring the viability of this leatherback turtle population.