TurtleWatch is a map providing up-to-date information about the thermal habitat of loggerhead sea turtles in the Pacific Ocean north of the Hawaiian Islands. It was created as an experimental product by the PIFSC Ecosystem and Oceanography Division to help reduce inadvertent interactions between Hawaii-based longline fishing vessels and loggerhead turtles. Derived from the best available scientific information, the TurtleWatch map displays sea surface temperature and ocean current conditions and the predicted location of waters preferred by the turtles.
Loggerhead sea turtles in the North Pacific are classified as an endangered species under the Endangered Species Act. By identifying the ocean habitat favored by the turtles, the TurtleWatch maps are expected to help longline fishing vessels pursuing swordfish or other fish species in the region deploy their fishing gear in areas where loggerheads are less likely to occur. In this way, NOAA Fisheries hopes to provide benefits not only to the turtles, but also to fishers, who operate under strict limits on the number of turtle interactions allowed.
Research by NOAA Fisheries scientists and their colleagues has provided a preliminary understanding of the thermal characteristics of loggerhead turtle habitat in the central North Pacific. Sea surface temperatures have been determined for the dates and locations of longline-loggerhead turtle interactions as recorded by NOAA Fisheries observers. Temperature data have also been compiled along ocean pathways used by loggerhead turtles that had been captured, equipped with temperature sensors, released alive, and tracked by satellite. The tracking work is a collaboration with the center's Ecosystem and Oceanography Division (EOD) and the Marine Turtle Biology and Assessment Program. Taken together, these research results indicate that most loggerhead turtles stay in water colder than 65.5°F (about 18.5°C). When the 65.5°F temperature contour is drawn on a map of the current sea surface temperature conditions, it delineates the current southern boundary of the loggerhead's preferred habitat. Over 50% of recorded loggerhead interactions occurred in waters between this southern 65.5°F boundary and the 63.5°F temperature contour to the north. TurtleWatch provides fishers with information on the location of the loggerhead's preferred thermal habitat (north of 65.5°F) and where the highest number of loggerhead interactions have occurred (red zone).
Sea surface temperature is measured remotely by NOAA satellite-borne sensors and compiled and processed daily by NOAA OceanWatch - Central Pacific. These satellite data are then mapped by EOD along with the 65.5°F temperature contour. Updated maps are posted on this web page as new temperature data become available and show the most recent prediction of loggerhead thermal habitat. To help avoid interactions with loggerhead turtles, longline fishers are advised to consult the latest map and fish in waters either warmer than 65.5°F or cooler than 63.5°F.
A large percentage of observed longline-loggerhead interactions have occurred in the first 3 months of the year when Hawaii-based swordfish longline vessels are most active. By providing the TurtleWatch product to longline fishers, NOAA hopes to decrease the likelihood of longline-loggerhead interactions during the first quarter of the swordfish fishing season.
For more information on TurtleWatch contact Evan Howell.