Using telemetry to mitigate the bycatch of long-lived marine vertebrates

The unintended bycatch of long-lived marine species in fishing gear is an important global conservation issue. One suite of management approaches used to address this problem restricts or modifies fishing practices in areas where the probability of bycatch is believed to be high. Information on the distribution and behavior of the bycaught species is a desirable component of any such scheme, but such observations are often lacking. We describe a spatially explicit approach that combines data on the distribution of fishing effort and observations of the distribution of bycatch species derived from satellite telemetry. In a case study, we used a spatially explicit predator-prey model to investigate real-time interactions between three species of sea turtles (Caretta caretta, Chelonia mydas, and Lepidochelys kempii) and the fall large-mesh gill net fishery that targets southern flounder (Paralichthys lethostigma) in Pamlico Sound, North Carolina between 2002 and 2004. The model calculates a spatial overlap index, thereby allowing us to identify which fishing areas have the greatest risk of encountering bycatch. In this study, our telemetry deployments (n=50) were designed specifically to address existing fisheries conservation measures in Pamlico Sound intended to reduce sea turtle bycatch. We were able to predict the spatial distribution of bycatch and evaluate management measures. This approach offers a powerful tool to managers faced with the need to reduce bycatch.