Expedition Great White: Catching the Ocean's Largest Predatory Fish

Nov. 13, 2009— -- Great white sharks. They're not just among the ocean's biggest creatures, they're among its fiercest.

They can detect tiny amounts of blood in water up to three miles away. They make about half of all the shark attacks reported in a given year.

But in National Geographic Channel's "Expedition Great White," which premieres Monday, scientists and sports fishermen do the unimaginable: They wrangle the multi-ton creatures, haul them aboard their ship, attach tracking tags, take measurements and DNA samples and then release them unharmed. All in the name of science.

The largest predators in the ocean (they can extend to more than 20 feet and exceed 5,000 pounds), great white sharks are listed as an endangered species because of overfishing, accidental catching and other factors.

Marine biologists and conservationists hope that by tagging them with tracking devices that transmit their locations, they'll be able to learn enough to protect the sharks' dwindling population.

Researchers Aim to Protect the Endangered Species

"The ecosystems are changing fast today with the amount of overharvesting. We don't want to see white sharks wiped off the face of the Earth," Brett McBride, captain of the expedition vessel MV Ocean, says in the National Geographic Channel program.

Along with Chris Fischer, the expedition leader, and Michael Domeier, the lead scientist, McBride and his crew traveled 150 miles off the coast of Baja, Calif., to catch and tag great white sharks.

The area near the volcanic island Guadalupe is known as a white shark "hot spot" because the sharks are attracted by the fur and elephant seals that gather there to breed.

"Guadalupe is heaven for white shark researchers," says Domeier, "It's really clear water and relatively warm."

As the sharks swim by to catch their prey, the scientists try to nab them with the world's biggest fishing hooks -- 24-inch circle hooks that effectively catch the corner of the sharks' mouths without harming them.

But catching a great white shark is a hard-won victory.

'Expedition Great White'

"When we drove up two years ago, [it was] the very first time we were going out there to do something that had ever been done on this scale. And we weren't sure how we were going to do it," said Fischer.

The team had experience and the right tools -- but that wasn't enough, at first, to take on the great whites.

Fischer said three sharks got away, destroying some of the ship's gear as they went.

The team eventually caught, tagged and released four other sharks.

But the tracking devices did not live up to expectations. Three out of four failed to transmit the sharks' location.

"Sample size is everything in science," said Domeier. Having one working transmitter attached to one shark, he said, is "good for television but it's not good for science."

So he went back to the drawing board. He worked with the manufacturer to create a tracking device with a longer-lasting battery and a stronger antenna.

When the team returned to Guadalupe, it was equipped with better technology and a refined system to catch the sharks.

The Art of the Chase

Once a shark takes the bait, a team of anglers on a 25-foot inflatable boat leads the shark away from the MV Ocean.

"It's critical that the chase boat team gets the fish away from the mother boat," said Domeier. "The main battle takes place a safe distance away."

The team uses fishing line that can hold more than 5,000 pounds and is attached to four weighted buoys. The chase boat battles the shark until it's tired out.

Then the crew members lead the shark back to the mother boat, where they carefully ease the shark onto a forklift-like platform attached to its side. The platform can hold 37 tons.

They raise the shark out of the water. Then begins a race against time.

They hydrate the shark's gills with a hose to keep it alive. They cover its eyes with a wet towel. They secure its tail.

From the moment the shark is hoisted out of the water, the team has only 20 minutes to measure the creature, bolt the tracking device to the shark's dorsal fin and take a blood sample.

'Expedition Great White'

Domeier said he hopes the tracking device and blood samples will provide valuable information about great whites' migration routes, how sharks around the world are related and, most importantly, the sharks' birthing process.

Females only give birth every other year, and scientists know very little about their habits.

"That puts them on some kind of two-year migration pattern but we don't know where they go. Now we have the tools to get the pieces to put the puzzle together," he said.

The work is exhausting and risky, and mysteries remain.

Said Fischer, "I don't care what kind of fishing you've done, there's no kind of fishing like this."

National Geographic Channel's "Expedition Great White" premieres Monday, Nov. 16, 2009, at 9 p.m. ET/PT. For more information, click here.