Turtles indeed in danger

Even though many sea turtle populations are declining, quantifying factors that contribute to declines has been challenging. Mortality occurs on nesting beaches due to habitat loss, egg poaching, and predation. But turtles also die at sea due to accidental catches in fishing gear.

In the March issue of Ecology Letters, Duke University researchers quantify incidental catch of loggerheads (Caretta caretta) and leatherbacks (Dermochelys coricea) in the global pelagic longline fishery. Despite infrequent encounters between turtles and longlines, the sheer magnitude of the longline fishery means more than 200,000 loggerheads and 50,000 leatherbacks were likely caught worldwide in 2000. Although not all encounters are fatal, thousands of hooked turtles die from bycatch each year.

The authors report that Pacific turtles vulnerable to longline hooks have about a 50% chance of being caught per year, which means more Pacific turtles die from longline takes each year than nest there. Given 80-95% declines for Pacific loggerhead and leatherback populations, this bycatch is not sustainable.

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