Influence of nearby environment on recreational bycatch of sea turtles at fishing piers in the eastern Gulf of Mexico

Abstract

Incidental bycatch of sea turtles from recreational fisheries is generally undocumented globally. At Gulf of Mexico fishing piers in the USA, bycatch is a source of injury and potential mortality of sea turtles. Recreational sea turtle bycatch has grown substantially over the last 6 yr, especially at the Navarre Beach Fishing Pier (NW Florida); the reasons for the increase and the impacts this has on the recovery of northern Gulf of Mexico sea turtle populations are largely unknown. In particular, the reasons why fishing piers are attracting sea turtles are not well understood or if the environmental context of other nearby habitats contributes to the bycatch. Using GIS, we analyzed potential environmental predictors of total sea turtle bycatch, across green sea turtles Chelonia mydas, loggerhead sea turtles Caretta caretta, and Kemp’s ridley sea turtles Lepidochelys kempii. We collated bycatch and environmental data from 20 Florida Gulf of Mexico fishing piers. We statistically assessed relationships using generalized additive models and selected the best fit model using the information-theoretic approach. We found that tonnage of nearby artificial reefs (based on defined home range and core use areas) and distance to nearest seagrass bed exhibit positive relationships with green sea turtle bycatch. For combined loggerhead and Kemp’s ridley bycatch, area of preserved water, distance to nearest seagrass bed, tonnage of nearby artificial reefs, and latitude of fishing piers were all predictors in the confidence set, but the shape of the relationships is variable and nonlinear. Further examination of sea turtle bycatch, occupancy of piers, and environmental factors pertaining to sea turtles will likely improve mitigation measures for recreational bycatch.