, Sept. 1 -- Just off the coast of New York's famous Hamptons beaches, marine researcher Greg Metzger reels in one of the day's most impressive catches - a young but powerful sand tiger shark.

Working quickly, Metzger and another researcher secure the sharp-toothed female shark alongside their boat. They collect tissue samples and attach small tracking devices before releasing it back into the ocean.

Metzger said the shark's tough skin was so strong that it could even damage a surgical-grade scalpel.

"It's no surprise that they've survived since prehistoric times and are still going strong," he said.

Metzger and other scientists are catching, tagging and releasing different species of sharks to better understand their populations and ...