Mapping Study Aims to Save Dwindling Leatherback Turtle Populations
By plotting the movements of GPS-tagged leatherback turtles and lining up the data with the locations of fisheries around the Pacific Ocean, researchers are able to predict the points of interaction of the turtles and the fisheries and subsequently reduce the number of turtles accidentally caught in fishing operations, according to a new study in the Proceedings of the Royal Society B.
The leatherback turtles is one of the most endangered turtle species, having declined in population by nearly 90 percent since the 1980s. The greatest source of mortality for these turtles is industrial longline fishing operations that catch fish by placing thousands of hooks in the water.
The researchers argue that by closing certain parts of the Pacific to industrial longline fishing at certain times, it will better the chances of the leatherback turtle's survival, as well as maintain the health of the commercial fishing industry.
"Given the size of the Pacific Ocean and the number of fisheries from dozens of nations that use it, managing bycatch is a complex issue," said lead study author John Roe, an assistant professor at the University of North Carolina at Pembroke. "To complicate things, fisheries authorities are not always forthcoming with information on when and where they capture turtles, so identifying problem areas, or hotspots, where bycatch likely occurs has proven elusive until now."
The fisheries have no intentions of catching turtles, but due to the style of their operations, turtles and other types of otherwise unwanted marine life wind up caught.
"Leatherback turtles get caught on longlines by both biting at the bait and getting entangled in the lines themselves," said James Spotila, a sea turtle expert at Drexel University. "Fishermen do not want to catch the turtles but have had limited success in avoiding them. Now they will be able to set their lines in areas where the turtles are unlikely to occur, making the ocean safer for turtles and reducing the cost to the fishermen of having to deal with the giant turtles."
The researchers contend that the information produced from their study could help protect leatherback turtles in particular because they are creatures of habit.
"Bycatch may be more easily avoided when areas of high risk occur predictably in space and time, allowing fisheries operators to adjust their efforts accordingly," Roe said. "Because leatherbacks follow paths that persist from year to year as they revisit the same nesting beaches, these areas provide an especially good opportunity for flexible regulations that serve the needs of both turtles and fisheries alike."
The researchers suggests that by adjusting fishery management practices in areas that have predicable leatherback turtle traffic, it will alleviate leatherback bycatch, which will help the species survive, as well as make the fishing operations more efficient.
"Now that we've scientifically homed in on where and when protections are needed, especially in the South Pacific Ocean the solutions to the turtle fishery problem will take international cooperation and innovative uses of technology to manage this wild west where regulations are few and enforcement is nil," Spotila said.