Shark attacks are not as big of a problem as many people think. Despite our fear of sharks, they kill fewer than 10 people in an average year. Humans, meanwhile, kill roughly 100 million sharks annually. That means we slaughter about 10 million sharks for every person who dies in a shark attack.
Any fatal shark attack is tragic, though, and it makes sense to try to prevent them. A few tactics are already used around the world, from shark netting and culling to less brutal — and possibly less effective — deterrents. Not only do these offer unreliable protection, but they can also add to existing woes for ocean ecosystems. Shark nets often snare turtles, dolphins and other animals as bycatch, and even when sharks are killed, their overall habitat may suffer from fewer keystone predators.
There is a simpler, more humane and more ecologically responsible way to thwart shark attacks, however: Just move the sharks somewhere else. It may sound too simple to work, but new research from Brazil's Shark Monitoring Program of Recife (SMPR) suggests it's at least worth a try.
The city of Recife, Brazil, has endured an uptick of shark attacks in recent decades, prompting a quest among local authorities to make their beaches safer. Although culling and netting had previously been used in places like South Africa, Australia and Hawaii, the decline of shark populations inspired Recife to find a non-lethal approach. So the SMPR simply caught live sharks and moved them farther offshore, where they wouldn't pose a threat to swimmers. Over an eight-year span, this resulted in 100 percent survival of protected species — and a 97 percent drop in shark attacks.
"With this strategy, we were able to reduce the rate of shark bites considerably while releasing most of the captured specimens alive," the study's authors write. "Furthermore, all potentially aggressive sharks were translocated to deeper waters and double tagged with acoustic and satellite transmitters upon release to assess their post-release behavior. This method allowed us to verify that such sharks did not move back to nearshore waters off Recife ... and did not experience post-release mortality."
A sign warns of sharks at a beach in Recife, Brazil. (Photo: Yasuyoshi Chiba/AFP/Getty Images)
Recife's original problem wasn't a surplus of sharks, the researchers add, but a set of "site-specific features in the region" that encouraged local sharks to encounter people, such as the construction of a commercial port nearby and the presence of an alongshore channel in the most hazardous area. Relocating the sharks offshore thus made more sense, they explain, than just killing them.
The Recife approach may not work as well on every shark-prone coastline, the researchers acknowledge, since it was developed specifically for local conditions and was tested in a relatively small area. Nonetheless, it shows that human safety and ecological sustainability are both possible in shark habitats. And that's especially relevant in light of Western Australia's controversial shark cull, a policy that has been widely criticized as a relic from less enlightened times.
"Scientists and environmentalists all over the world are concerned about lethal shark control measures like those used in Western Australia," says David Shiffman, a marine biologist and blogger for Southern Fried Science who wrote a commentary about the study in the journal Animal Conservation. "This research shows that non-lethal techniques can help make swimmers safe."
Related shark stories from MNN:
- 11 animals more likely to kill you than sharks
- Why sharks generate more money alive than dead
- Great white sharks can live as long as humans