Tagging Marks the Sharks

Determining the number of sharks in the ocean and figuring out exactly where they go are among nature's great mysteries.

Beyond their lack of warm and fuzzy features, sharks are anti-social, preferring to hunt and travel alone, which makes tracking them even more difficult.

So, CBS News Science and Technology Correspondent Daniel Sieberg traveled to the Bahamas recently as part of the "Early Show" and Discovery Channel's "Shark Week" partnership. Sieberg told of joining a shark-tagging experiment on "The Early Show" Wednesday.

Why tag sharks?

Andy Dehart, a marine biologist, told Sieberg, "It's really important to know where sharks go, so we can preserve them."

Sieberg explained tagging helps scientists understand how factors such as climate change and food supply affect the migration behavior of sharks.

But actually tagging a shark, Sieberg said, is an extremely tricky task.

Sieberg saw the process up close when he dove with researchers and members of the Stuart Coe diving operation in Nassau, Bahamas, as they assisted with a Canadian study on Caribbean reef sharks.

Liz Parkinson, a shark wrangler, told Sieberg she's been bitten more than once.

"I've been bitten a couple of times," she said. "It's kind of the adrenaline rush of the moment, but once you realized what happened you're like 'Oh my God, I've been bitten by a shark." '

To reduce the risk of being bitten, the divers doing the tagging wear metal suits called chain mail.

Dehart instructed Sieberg when he was swimming with the sharks to keep his hands near his body: "Sharks see contrast in color so our white hands could potentially look like a bit of fish. So that's why we keep our hands in close."

Since tagging a shark underwater could be like riding a bucking bronco with razor-sharp teeth, Sieberg said, a technique called "tonic immobility" is used.

The technique, Sieberg explained, is a kind of stimulating massage near the shark's nose that calms the sharks for a brief period. (Editor's note: Please do not attempt.)

"Certainly we can't take it for granted," Dehart said. "We always have to respect these animals ... The amazing thing is who would have ever thought you could grab a shark, hug it, put it to sleep, and then tag it."

The tagging occurs quickly near the shark's fin. Though the tagging looks uncomfortable for the shark, Dehart said, it's the pressure of the applied tag that the shark doesn't like.

If the sharks are caught by fishermen, Sieberg said, a reward is offered for details about the animal, including where the catch was made.

Electronic tags are also being tested in the Bahamas. These tags send a "ping" to underwater receivers any time the shark swims nearby.

Sieberg said the goal of tagging is to get a better look at the highly-evolved animals.

"My direct goal is to make everybody love sharks," Dehart said. "But I know there will always be some sense in our minds a little fear of sharks, but that's also fear of the unknown. We're dealing with the ocean environment. We're not overly comfortable with that."

Sieberg added researchers hope people will learn to appreciate sharks as not simply mindless eating machines, but rather as creatures in need of care to conserve their dwindling numbers.