Following The Trail Of The Whale Shark

Aug 25, 2013
Originally published on August 25, 2013 11:30 am
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RACHEL MARTIN, HOST:

Of all the creatures in the sea, one of the most majestic and mysterious is the whale shark. It's 30 feet or more in length and it weighs around 10 tons. Scientists have long wondered about where the whale shark migrates and where it gives birth. Now, scientists have completed the biggest ever whale shark study. And as NPR's Christopher Joyce reports, they think they have some answers.

CHRISTOPHER JOYCE, BYLINE: Marine biologist Robert Hueter swims with sharks. He's been doing it for 40 years. But he has a special fondness for whale sharks.

ROBERT HUETER: This is the largest fish as far as we know that's ever existed. But it's a very unusual kind of shark in that it's not a top predator, it feeds on plankton.

JOYCE: Plankton are the flotsam of tiny plants and shrimp-like animals that float in the ocean. The whale shark just opens its mouth - about twice the size of a manhole cover - and sucks them in. Hueter was studying some regular meat-eating sharks in the Yucatan Peninsula of Mexico when he came across whale sharks feeding. It turned out to be the world's largest concentration of whale sharks - over 400 of them. Hueter was smitten.

HUETER: It's polka dotted. And it lets people swim with it. When you go down and see them at these feed aggregation sites, it's a spectacle of nature. It's unlike anything else that you'll ever experience.

JOYCE: Hueter directs shark research at the Mote Marine Laboratory in Sarasota, Florida. He organized a project to tag whale sharks. Many of these tags record where a shark goes, how deep it dives and the water temperature, and relay the data back to his lab via satellite. Hueter attached many of these tags himself by hand.

HUETER: Your heart starts racing every single time because you're just next to something that's just so huge.

JOYCE: After tagging more than 800 whale sharks over nine years, the team discovered that after feeding, the sharks head off in seemingly random directions. Some travel thousands of miles, and they can dive a mile deep. One female in particular - they called her Rio Lady - swam to the middle of the Atlantic, between Brazil and Africa, and just hung out. So, what was she doing there, they wondered? Hueter suspects that she was giving birth - to pups, in the shark vernacular - out in the open ocean, perhaps a safer place for young pups.

HUETER: We think that Rio Lady has led us to the place where this particular species gives birth.

DEMIAN CAMPBELL: For most sharks, that's often times the million dollar question: where they give birth.

JOYCE: Demian Campbell studies sharks at Stony Brook University in New York.

CAMPBELL: Nursery areas are places usually close to the coast, so giving birth in the middle of the ocean is sort of a fairly unusual thing for sharks to do.

JOYCE: Hueter describes the research in the journal PLOS One. He says the whale sharks' far-flung travels demonstrate that protecting this rare species will require international collaboration, not unlike the protection given migrating Bluefin tuna. Already, the research has led Mexico's government to protect the sharks' big feeding grounds there. Christopher Joyce, NPR News.

MARTIN: This is NPR News. Transcript provided by NPR, Copyright NPR.