Love for sea leads to study of sharks

Hammerheads ‘Oddly Beautiful’


Neil Hammerschlag loves the ocean.

He began snorkeling before he was 5 years old, became a certified diver at 11, a master diver at 18 and now has nearly 400 dives behind him. As a child, he says, he “read every book about the ocean.”

“A lot of kids want to be things like astronauts and firemen,” said Hammerschlag in an interview at the University of Miami’s Rosenstiel School of Marine and Atmospheric Sciences. “I wanted to be a marine biologist.”

Hammerschlag, 32, grew up to become a specialist on sharks – creatures that scare the daylights out of many people and that he and other scientists believe play an important role in the healthy balance of the oceans and the rest of the environment. His research has shown that sharks affect the life and death of coral reefs. Some researchers say they may also influence the capacity of oceans to absorb the carbon dioxide that contributes to global warming.

Hammerschlag is as crazy about sharks as he is about the ocean. He knows that tens of millions of sharks are killed each year by commercial fishermen and he worries about their survival. He believes that if research can demonstrate their value, the killing may stop, or at least be slowed.

Just how sharks affect the environment is not entirely clear. And that is the focus of Hammerschlag’s work. “We know more about outer space than we know about the ocean,” he said, “and even less about sharks. Everyone says sharks play a role in the environment, but it’s hard to know what the role is.”

Shark research is high on the agenda at the Rosenstiel School and at its R.J. Dunlap Marine Conservation Program. Hammerschlag is a research professor at Rosenstiel and the founder and director of the Dunlap Program, which also studies barracudas, mangroves and blue-green algae – and the possible relationship of the algae to Alzheimer’s and other diseases.

Hammerschlag, who earned his PhD at the Rosenstiel School, focuses on three kinds of sharks – hammerheads, bulls and tigers. But he is really fascinated by the biggest of the hammerheads, the great hammerhead. “They’re mysterious,” he said. “Oddly beautiful.”

Hammerschlag uses satellite tracking devices that enable him to follow an individual shark for weeks over hundreds of miles. One of his findings has been that hammerhead sharks cruise over a much larger span of the ocean than was previously known. They had been thought to mostly stay relatively close to the Atlantic coast of the United States. But by bolting a radio transmitter to a shark’s dorsal fin and tracking it via satellite, Hammerschlag saw that the fish swam 300 miles or 500 kilometers out to international waters where commercial fishing fleets from many countries operate.

That puts the sharks at great risk. Their fins sell for more than $300 a pound as the essential ingredient in shark fin soup. Without any scientific evidence, many people say this soup increases sexual potency and helps prevent heart disease.

Environmental groups have been lobbying to ban fishing for shark fins. But it is a billion-dollar-a-year business and the killing is not expected to end anytime soon. Discovering that the hammerheads are often in harm’s way was a first step in saving them, Hammerschlag said: “In order to protect them, you need to know where they are.”

Hammerschlag and other marine scientists say that sharks are needed to keep algae from smothering coral reefs and to prevent the disappearance of huge amounts of plant plankton that help the ocean absorb more carbon dioxide from the air than all the world’s forests.

Routinely, parrotfish eat the algae on coral reefs. But when the number of sharks drops, because of heavy fishing, perhaps, the reef fish that sharks usually eat, like grouper and snapper, become more abundant. As a result, more parrotfish get eaten. With fewer parrotfish around, the algae begin to take over the reef. “By removing the sharks,” Hammerschlag said, “you end up killing the coral.”

That cascading effect along the food chain may demonstrate a role sharks have in the pace of global warming. Phytoplankton, microscopic plants in the ocean, absorb huge amounts of carbon dioxide from car exhaust and factory smoke as it settles out of the sky. Like trees, the little ocean plants create the oxygen that people breathe. Lots of fish eat the tiny plants. Sharks routinely eat many of those fish. Without the sharks, the scientists say, the fish that gobble up the plankton could multiply and greatly reduce the mass of little plants that pull in carbon dioxide and pump out oxygen.

As a small boy in South Africa, Hammerschlag saw sharks trapped in nets designed to protect swimmers. On the beach, the sharks were slit open to see what they had eaten. He had already started snorkeling and as time went on he realized that his life was going to be the oceans.

His family moved to Canada to get away from the social upheaval and street crime of South Africa and he eventually enrolled in an ecology program at the University of Toronto. An internship at the Pelagic Shark Research Foundation in Santa Cruz, Calif., changed his life. “I loved all marine life,” he said, “and it was difficult to have a focus. I worked on coral–all kinds of things.” But once he started working with sharks, he said, “I never looked back.” #

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