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Endangered sea turtle populations show signs of recovery in more than half the world, survey finds

Endangered sea turtles show signs of recovery in a majority of places where they're found worldwide, according to a new global survey released Thursday.

"Many of the turtle populations have come back, though some haven't," said Duke ecologist Stuart Pimm, who was not involved with the research. "Overall, the sea turtle story is one of the real conservation success stories."

The study looked at 48 populations of sea turtles around the world. Scientists measured the impacts of threats such as hunting, pollution, coastal development and climate change to the marine animals. In more than half of the areas studied, threats are declining overall, the study found.

But there are some exceptions. Sea turtle populations in the Atlantic Ocean are more likely to be recovering than those in Pacific waters. And leatherback turtles are not faring as well as other species.

Globally, leatherbacks are considered vulnerable to extinction, but many groups are critically endangered, according to the International Union for Conservation of Nature.

All seven of the regions where leatherbacks are found face high environmental risks, said study co-author Bryan Wallace, a wildlife ecologist at Ecolibrium in Colorado.

Leatherback turtles are famous for making the longest known marine migrations of any animal—with some individuals swimming as many as 3,700 miles (5,955 kilometers) each way. That feat moves them through a wide swath of regions and may expose them to unique risks, he said.

Meanwhile, green turtles are still considered endangered globally, but their populations show signs of recovery in many regions of the world, researchers found.

"By ending commercial harvests and allowing them time to rebound, their populations are now doing really well" in coastal waters off many regions of Mexico and the U.S., said co-author Michelle María Early Capistrán, a Stanford University researcher who has conducted fieldwork in both countries.

Sea turtles were protected under the U.S. Endangered Species Act of 1973, and Mexico banned all captures of sea turtles in 1990. But it took a few decades for the results of these actions—alongside efforts to protect nesting beaches and reduce accidental bycatch in fishing—to show up in population trends, she said.

Around the world, the problem of sea turtles dying after accidentally becoming entangled in fishing gear remains a major threat, said Wallace. New technologies are being developed to spare turtles, but they must be accepted and used regularly by diverse fishing communities to be effective, he added.

The survey in the journal Endangered Species Research and is the first update in more than a decade.