Abstract
Fisheries by-catch and incidental mortality is an issue that continues to plague conservation efforts of many marine megafauna species. Marine turtles are particularly susceptible due to life history characteristics, like delayed reproduction and long migrations (Bolten, 2003). Regulations on gear types and fishing closures were implemented in the early 2000’s (NOAA Final Rule (69 FR 40733, 07/06/04)), but re-examining trends in sea turtle by-catch could reveal high-risk areas that are not addressed by existing management protections.
Commercial longline sets are particularly threatening to marine turtles due to the hook depth and bait types they tend to use (Lewison et al., 2004, Swimmer et al., 2017). Sea surface temperature (SST) is also an indicator of the likelihood of interactions between turtles and fishing gear. The objective of this study was to assess where loggerhead turtle and pelagic longline interactions have most often occurred and compare these hotspots to established management areas. As ocean conditions have shifted because of climate change, is by-catch management still overlapping with high-risk areas?
This study used NOAA’s fishery-dependent scientific observer data for U.S. longline fleets in the Atlantic that targeted primarily swordfish and tunas. Remotely sensed SST data from AQUA/MODIS satellites was also integrated. Using ESRI’s ArcGIS Pro, a multi-step process created a hotspot model that incorporated set characteristics, by-catch events, and SST within the U.S. North Atlantic Exclusive Economic Zone (EEZ). With incidental sea turtle capture estimated to be over 25,000 individuals per year in the Atlantic (Gray and Diaz, 2017), ensuring that management is adapting to shifting habitat regimes is vital to the protection of turtle populations in the U.S.