In the Toronto Star, Sandro Contenta travels to the Bahamas to attend “SharkSchool” where a man named Erich Ritter teaches a one-week course on how to swim safely with sharks. Over the course of his reporting, Contenta learns that 63 people have been killed by sharks in the past decade, while scientists have estimated that 97 million sharks have been killed by humans during fishing-related activities in 2010 alone:

The scientists concluded that dozens of species of sharks were being killed at unsustainable rates. “The consequences of these unsustainable catch and mortality rates for marine ecosystems could be substantial,” they wrote. “Global total shark mortality, therefore, needs to be reduced drastically in order to rebuild depleted populations and restore marine ecosystems with functional top predators.”

Scientists warn of a “trophic cascade.” That’s when the disappearance of a top predator causes a cascading and dramatic impact on organisms at lower levels of the food chain until an entire ecosystem is transformed. The loss of sharks, for example, contributes to the death of coral reefs, because coral-eating fish that were part of a shark’s diet suddenly boom in numbers.

Worm and his colleagues echoed concerns by the International Union for Conservation of Nature, published in a landmark analysis by 23 leading scientists including B.C.’s Nick Dulvy, who co-chairs the union’s shark specialist group. Released in January, the 34-page report is based on the work of more than 300 scientists. It is the first systematic analysis of the global population status of more than 1,000 species of sharks, rays and chimaeras.
It found that one in four of these fish are threatened with extinction due to overfishing, either targeted or unintended, what the fishing industry calls bycatch. That amounted to 107 species of rays and 74 species of sharks, including angel and thresher sharks.

“There isn’t a part of the ice-free ocean surface that doesn’t contain a threatened shark,” Dulvy says. “That’s a lot of real estate with threatened biodiversity.”

As for what you should do if you ever found yourself being attacked by a shark? The answer is obvious: Fight for your life:

“In sharks you want to fight and fight like hell because they respect power,” Burgess says. “If you pop them in the nose, they veer off almost always, and then will come back around.

“I equate it to the neighbourhood bully: if you pop them in the nose first, more often than not they’ll back off because they weren’t expecting it. After the initial surprise wears off he’ll probably come back and beat the hell out of you, and you’d be smart to get out of the water while you’ve got your opening.

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Photo: Jeff