1. Shark repellent
2. How dangerous?
3. Shark lovers
4. A social killer?
Caribbean reef shark. Courtesy Grant
Biological Field Station
This bloke is cutting the fin off a great hammerhead
shark. Will he dump the carcass of this magnificent predator
into the drink? Photo: Bimini
Biological Field Station
Say "Ahh." Meet the business end of a white
M.C. Scholl, Wildlife
This satellite tag can track white sharks
almost in real time. When the shark surfaces, the tag dumps
data to a satellite. Courtesy M.C. Scholl, Wildlife
The flip side of shark-o-phobia is a fascination with these oceanic predators. Partly because sharks are so powerful in their element. And partly because they are an evolutionary success. These predators are ancient, widespread (almost 500 species in essentially all parts of the oceans), and highly crafted to making a living in salt water. They have unusual sensory capabilities, including sensitive detectors for electrical field emitted by prey hidden under sand or in murky water.
"I like them, think they are really cool," says Samuel (Doc) Gruber of the University of Miami. "They have this undeserved reputation, but once you get to know some personally, you have studied them and understand a little about their biology, natural history and capabilities, you become impressed, amazed. And when you find they are being decimated, pushed to the brink of extinction, you become angry, become a proselytizer."
Sharks may be at the top of the food chain, but as we mentioned, they have "PR issues," and are slaughtered by the millions. Some die accidentally, caught on hooks set for tuna or swordfish, or in nets set for other fish. Others are killed for their fins, which are valued in Chinese celebrations. Gruber says a surfboard-sized fin from a basking shark can fetch $5,000. The carcass is usually dumped into the sea.
The exact number of sharks killed is unknown. "You often see the number 100 million," says Bonfil of Wildlife Conservation Society, "but there's no basis for that number." His best estimate is something below 50 million.
That's a raft of dead sharks, and it helps explain population losses of at least 75 percent since 1985 among scalloped hammerhead, white, and thresher sharks along the U.S. and Canadian coasts (see "Collapse and Conservation..." in the bibliography).
Much of the fear focuses on the white shark, AKA the great white shark, which is the predominant cause of shark attacks. This predator can be 18 feet long and weigh more than two tons. It's got mobility. It's got vision and other underwater senses. It's got serious chompers.
Whites often kill from curiosity, says Bonfil, who is studying them in the Indian Ocean off South Africa. In many cases, he says, "they are investigating what we are, to see if we could be eaten. By the time they find out whether they like us or not, you might be bleeding to death. ... They may not be interested, but you may have lost leg or something."
Some sharks are less discriminating, he says. "Bull sharks are not picky about what they eat. So if you get in the way of a hungry bull shark while it is searching for food, you will be taken almost for sure."
Bonfil doesn't have much truck with people who blame sharks for being sharks. If you're in their habitat, he says, you may become "part of the food chain. It's like a dog that might be eaten by a wolf or cougar. If you wander into the sea, you might be eaten by a shark. It's a risk we have to take, if we invade their territory."
Still, sharks aren't generally waiting to scare the swimming trunks off foolhardy Homo sapiens, Bonfil says. "There is this image of the shark as a super-aggressive, malicious fish. I have worked with white sharks at close range. In their natural behavior, they are almost gentle, really shy animals."
During tagging operations, Bonfil says, "They don't want to come close. If we move too fast, they get scared and go away. It's absolutely not what Hollywood has tried to make out."
For three years, Bonfil has been tagging white sharks in the Indian Ocean. Bonfil says some whites stay in a small area for a couple of months, while others disappear for a couple of weeks, then return. Some move between bays located a couple of hundred miles apart on the coast. A number of sharks, Bonfil says, "take very long migrations, and return after several months, right back to the same place they were tagged. This is something surprising that nobody had documented before."
White sharks normally cruise at two or three kilometers an hour, Bonfil has found.
As a counterweight to shark exploitation, how about shark ecotourism? A number of boat operators in South Africa make a living scaring tourists to within an inch of their lives in shark cages. Business seems good, says Bonfil. "I have not heard them complaining that they don't have enough clients." Most thrill-seekers tourists come from Europe or the United States, he says.
Want to dive with the white sharks off South Africa?
Here's your ticket to ride. Photo: White
Shark Diving Tours
Shark tourism beats shark-killing, Bonfil says, and while some operators do a good job of explaining the shark's ecological role, "some don't treat the sharks nicely, or push the image of the aggressive, mean shark."
In theory, he concludes, "Ecotourism, when done right, is the best tool to counter consumptive use. Instead of chopping them to pieces and selling and eating them, it keeps them alive, and you can still make money from them."
Sharks: Lone predators or social animals?