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Biologist dives in at feeding frenzy
There’s a shark frenzy, and one researcher jumps in.
Rare look at sharks is whale of a tale
As several large tiger sharks tore apart a whale carcass off Key Largo, biologist Neil Hammerschlag made what many would consider to be a poor life choice.
He went into the water to get a better look. A shark specialist at the University of Miami, Hammerschlag has published articles on the behavior of sharks feeding on dead whales, but had never seen it firsthand.
Friday morning, he heard that a whale carcass had been spotted in the Gulf Stream. Aware of what was likely to be found eating it, he found a dive company that would take him out on waters made rough by the approach of Subtropical Storm Alberto.
After fruitlessly searching for hours, they saw a boat in which people had crowded into the bow to look into the ocean. As they got closer, they saw a giant clump of fat and tissue — “like a big, melting ice cream blob,” Hammerschlag said — with fins slicing through the water around it.
“We could see the sharks would swim up and take a big bite and shake their heads back and forth to cut into the flesh,”
he said.
At least five tiger sharks, ranging in length from 10 to 15 feet, were devouring the whale’s remains.
Although getting into the water with a bunch of hungry sharks may seem foolhardy, Hammerschlag didn’t see it that way. Experienced in diving with sharks, he had another diver watch his back and stayed near enough to the boat to jump back in. And he saw this as a once-in-a-lifetime opportunity to observe a process that’s crucial to the ecology of the oceans. Like an old tree falling in a forest, a dead whale that sinks to the ocean floor provides years of food and habitat for a vast range of creatures that scavenge its tissue and bones, a process facilited by the sharks.
“You see what an important role these sharks play in the ecosystem,” said Hammerschlag, research associate professor at UM’s Rosenstiel School of Marine & Atmospheric Science. “They’re recycling this whale back into the food web.”
Hoping to avoid being recycled back into the food web himself, he kept his distance. He noted the fact that only a single shark species appeared to be present. And unlike the great white sharks of South Africa, which attack a carcass simultaneously, the tiger sharks went one at a time.
“They’re all taking turns,” he said. “One would go in and then leave and then the next one would come in.”
But these well-mannered sharks responded poorly to the prospect of anyone else joining the dinner party. As soon as Hammerschlag came too close to the carcass, the sharks turned and went at him, coming within a foot of him, showing their teeth before veering off.
“They would come close and turn, showing me the length of their body, and make a wide turn out and do the same thing, and then the next one would do it,” said Hammerschlag, who is also director of UM’s Shark Research & Conservation Program. “Maybe they were trying to push me off or intimidate me. They’re not territorial. But you got a sense they were guarding this carcass. Maybe they saw me as a competitor.”
Tiger sharks are included in what’s sometimes called the unholy trinity of shark species responsible for the largest number of unprovoked attacks on people. The other two are the bull shark and the great white. Was Hammerschlag nervous about approaching such sharks, especially when they were in an eating frame of mind?
“A little bit,” he said. “I’ve been in the water a lot with sharks. It was a bit nervewracking. I had someone with me from the dive center who was watching my back. It was just unnerving when they starting coming into my peripheral vision and surprising me. They were interested in the carcass, not in me. It was only when I got too close.”
The odds were in his favor. Sharks kill six people a year on average, according to the International Shark Attack File. By comparison, people kill an estimated 100 million sharks each year for meat, fins or as accidental catch in other fisheries.
Hammerschlag doesn’t consider himself a daredevil and doesn’t want to come off as one. He was simply an experienced scientist and diver who knew how to keep the risks low.
“I was very cautious in the way I did it,” he said. “I wouldn’t recommend that anyone try this.”