VOA标准英语2015--科学家寻找更好的途径解决鲨鱼面临的威胁（在线收听）

Scientists Seek Better Understanding of Threats Faced by Sharks 科学家寻找更好的途径解决鲨鱼面临的威胁

COCONUT ISLAND, HAWAII—

With many shark species endangered or threatened as a result of pollution and other problems, scientists are getting a shark’s-eye view of their environment to better understand the dangers they face.

A University of Hawaii research site on Coconut Island, minutes by motorboat from the shore of Oahu, is a good place to observe sharks, since they’re native to local waters. Some are kept in a sheltered bay for study.

Carl Meyer does research on "when sharks are feeding and hopefully how much they’re eating. That’s what we use these captive animals for.”

Scientists also monitor the behavior of sharks at sea, placing sensing pellets in their food to monitor digestion, measuring the animals and then releasing them with radio-equipped electronic tags attached to their fins. The researchers study tiger sharks, sandbar sharks, blacktip sharks and others, and they recently fitted a sandbar shark with a camera for a rare shark’s-eye view of its daily activities.

“When we recovered the camera," Meyer said, "we saw that the shark had spent the day in a large aggregation of sharks, not just sandbar sharks but also blacktip sharks and many, many scalloped hammerhead sharks.”

Sharks are swift and lethal, but don’t usually prey on humans. Meyer said the rare attacks are amplified by the media and dramatized in films like the 1975 thriller "Jaws."

He said sharks are important top-level predators that help maintain the balance of the marine systems. Those systems are threatened by pollution, climate change and commercial fishing, as fishermen target sharks for the Asian food market and kill them in the process of harvesting other species.

Meyer said humans are more of a risk to sharks than sharks are to humans.

"Never before in the natural history of the world have we seen a species become so dominant and so able to alter the natural environment,” he said.

And the results of those environmental changes cannot always be predicted, he said.