The oceans are ailing. Marine biologists say there are many reasons -- pollution, coastal development. But a key problem is overfishing. Among the marine species threatened by overfishing are sharks. Millions are killed each year for their fins, which are a delicacy in Asia. The World's Julia Kumari Drapkin met two researchers trying to save sharks. She reports from the waters off Mexico's Yucatan Peninsula.
Drapkin: Two divers chase a giant whale shark where the Gulf of Mexico meets the Carribbean. The water is milky green. The shark's speckled skin scatters the sunlight above. One diver, Rachel Graham takes photographs. The other, Dan Castellanos tags it with a spear. By the time they make it back to the boat, the shark has given them quite a work out.
Graham: "He made us run!" Castallanos: "My legs..."
Drapkin: Graham and Castellanos are fitting sharks with electronic tags to track their migration. They've tagged over two hundred sharks off of Belize, Cuba, and Honduras. And here in Mexico where they've tagged two more today.
Castellanos: "I tagged the first one, she got the second one." Graham: "We do tag team. Forgive the pun. I'll tag one, he'll do the photo id and check for sex. And then he'll tag one, and I'll do the photo id."
Castellanos and Graham
Drapkin: Rachel Graham and Dan Castellanos make an unlikely team. She's tall and blonde - half British, half American. She grew up in Tunisia. He's tall and dark - half Guatemalan, half Garifunan. He grew up in Belize. She's been fascinated with sharks since she was 4 yrs old. She decided to study and protect them. From the time he was a child, he killed sharks.
Castallanos: "We used to get tons of shark."
Drapkin: He used to fish with his dad
Castallanos: "For a whole range of shark. All the predatory sharks. Pretty much supporting the family."
Drapkin: Supporting the family meant dropping out of school to fish, and sharks were the easiest fish to catch.
Castallanos: "There was a good price for it also, for the meat and the fin."
Whale shark
Drapkin: Castellanos grew up in a fishing village called Monkey River. And that's where Rachel Graham came almost a decade ago to do graduate research on sharks. She needed a boat and a captain. So she hired Castallanos. And right away she was impressed .
Graham: "There I was studying for my PhD and Dan already had a PhD of the sea."
Drapkin: Castallanos, the firsherman, taught Graham the biologist the sharks are easiest to find during new moons. At the same time, he started learning from her.
Castallanos: "The shark keeps a balance."
Drapkin: As a child he thought the only value sharks had was on a dinner plate. But she taught him about the natural food chain. Sharks eat other fish that eat even smaller fish that eat algae. Without sharks, the other predatory fish eat too many small fish.
Castallanos: "Where there is no shark the reef, a lot of algae has started to take over."
Drapkin: When a reef gets taken over by algae, the health of the whole ecosystem suffers.And the fishermen suffer too. So Castellanos became a shark conservationist. And Graham's research partner. Together they study several types of sharks. But the species they're tracking most closely is the whale shark.
Graham: "How exciting another shark. Ooooooh!"
Drapkin: Graham gets excited by every whale shark they tag. Every tag helps them know more about this species. It's the largest fish in the sea. But very little is know about these animals. Like where they go and how they reproduce. Scientists do know that whale sharks can grow up to 40 feet long, and weigh up to 15 tons.
But they're gentle, they feed on plankton and the eggs of spawning fish. They travel the oceans mostly alone but sometimes they gather where food is abundant
Like here off the coast of Holbox Island in Mexico.
Graham: "From what we've found out, it looks like the Holbox aggregation is the largest most predictable aggregation of whale sharks in the world."
Drapkin: The sharks travel here from Belize, Honduras , and Cuba. Predicting where the sharks are going to be and when helps scientists protect them. Conservationsists created a marine reserve in Belize, based in part on Graham's research. Graham and Castellanos are now helping to create a marine reserve in Mexico too.
But Graham and Castellanos have produced more than research. They've had two sons and have made a home together. The family lives on a farm in Belize. Castellanos the fisherman and Graham the scientist have been a couple for five years now. And they're still making discoveries - about each other.
Castallanos: "Myself I used to be scared of sharks, and watching you swim around with shark I was like, wow."
Graham: "Were you scared of shark? Yeah. I didn't know you were scared of sharks! I think you've gone from someone being very scared of sharks to not being scared in the least. Also you've passed on this message sharks are quite amazing fabulous creatures to a lot of your friends and family -You're dad - Mr. Shark fisher! "
Castallanos: "Even my best friend. Sharks are friendly, they're curious."
Drapkin: Castellanos and Graham are raising their sons to be curious about sharks too. Their five-year-old, Xavi, swims with whale sharks. He also fishes with his grandfather. And he knows that an ocean full of sharks helps ensure a good catch.
