研究：航运对世界上最大的鱼类构成重大威胁

Marine biologists have noticed that whale shark numbers have been falling in recent years. But the scientists have not known exactly why.

A new international study suggests that collisions with shipping traffic could be a major reason for the decrease.

The study was led by the Marine Biological Association of the U.K. and the University of Southampton, along with experts in Australia and New Zealand. The study appeared in the publication Proceedings of the National Academy of Sciences.

Researchers examined satellite data to observe about 350 whale sharks. They found that the world's largest fish spend most of their time in waters used by large shipping boats.

The study showed that information from the devices used to observe their movements often ended in busy shipping paths. The researchers believe many sharks are probably being hit and killed by boats before sinking to the ocean floor.

Mark Erdmann is with the University of Auckland in New Zealand and a scientist at the non-profit environmental organization Conservation International. He was one of the writers of the new study. Erdmann believes shipping is a major threat to whale shark populations.

"...What the study found is that, indeed, there is a tremendous amount of overlap between where whale sharks are moving and global shipping traffic. So, those are real collision-risk areas," he said.

Whale sharks can grow up to 20 meters long. They play an important part in providing healthy ocean environments.

Most deadly strikes between whale sharks and boats are likely to go unobserved or unreported. There are currently no laws to protect whale sharks against these kinds of collisions.

I'm Jonathan Evans.

Phil Mercer reported on this story for VOA News. Jonathan Evans adapted this story for Learning English.

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marine – adj. of or relating to the sea

collision – n. an act or instance of colliding

tremendous – adj. astonishingly large, strong, or great

overlap – v. to extend over or past and cover a part of; to have something in common