The attack of a 40-year-old swimmer by a great white shark in southern California on Saturday has people questioning shark fishing and beach safety.
The man survived the attack with serious bite injuries. The shark, said to be a 7-foot-long (2.1 meters) juvenile great white, had been hooked on a line by an angler off the Manhattan Beach pier. The fisherman had been unable to bring the beast in, so he reportedly cut the line.
The panicked, exhausted animal then bit long-distance swimmer Steven Robles on the chest.
National Geographic spoke with George Burgess, the director of shark research at the Florida Museum of Natural History in Gainesville and the curator of the International Shark Attack File, about the incident and the gradual rise in shark encounters since the year 1900, when reliable records began. (See "How Should We Respond When Humans and Sharks Collide?")
Were you surprised by the attack in California?
That one in California was what we call a provoked attack, because there was human provocation involved. In this case humans are the villains, not the shark, [which] was hooked ... by an angler at the time of the attack. Obviously that's a provocation. Any animal that's fighting for its life has to be cut a little break in terms of being irritable.
How common are such provoked attacks?
They're not very common; we see a few a year. This one was especially unusual. You don't usually have shark fishing and swimming together.
There [have been] a few attacks where sharks [have been pulled] onto a boat, and then fishermen have tried to remove the hooks. And sometimes you get "stupid human tricks," [like] when a diver will grab a shark by its tail. Other provoked attacks include spearfishing incidents and accidents when sharks are attracted by bait. In the California case the fisherman was reportedly using chum, so that would make it a double whammy.
You recently pointed out that the number of shark attacks over time appears to be on the rise. Is that still the case?
Yes. We can reasonably predict that it will continue, as long as human populations continue to rise and more people keep going into the water.
Conservation is becoming more effective, [increasing] populations of declining sharks. But the human population seems to be the most important variable.
According to the International Shark Attack File, which you curate, 2013 had 72 unprovoked attacks—the lowest number since 2009. Any idea why there was a dip last year?
We don't know exactly why. There is variation year to year because of local environmental issues, such as changes in climate, storms, availability of prey, and so on. If you look at the long-term trends, you'll see there's an increase. We continue to have more attacks even though we continue to have [fewer] sharks around the world. That's because if you put enough people in the water, there can be trouble.
In South Africa shark attacks tend to [increase] in years when they have big sardine runs along the coast, because that brings sharks to the area. In Florida there tend to be fewer attacks in years when there are many hurricanes and tropical storms, because [those get] people out of the water. Economic and social conditions also affect the trend, because sometimes many people simply can't afford to go to the beach or take a vacation.
Is global warming playing a role in the overall increase of shark attacks?
Yes, I think so. Most sharks are warm-water animals, and as water temperatures increase the animals are extending their ranges. Warmer water also means extra days that people are in the water, and that will mean more encounters. (See "Scientists Track Great White Across Atlantic for First Time.")
Some people in southern California have questioned whether shark fishing should be prevented in areas where people swim. Would you agree?
We shouldn't be fishing for sharks and swimming in the same place—that's a no-brainer. California officials should be evaluating the wisdom of allowing those two things to take place [at the same time].
It's also not real smart, in areas with great white sharks, to have a swimming beach right next to a seal beach, which is what you see in some other areas. Juvenile great whites like the one involved in the attack Saturday generally eat fish, but adult great whites eat seals. Swimming near seal beaches can be dangerous.
In general, how are great whites faring these days?
We just published two papers on great whites in the last two weeks—one on the Atlantic and one on the Pacific—and we found that great white shark populations are on the rise. (See "Great White Sharks Thriving in U.S. Waters.") Not hugely, but they are on the return trip back up after being in a valley.
There have been some conservation measures, but the main reason is fisheries management. Most sharks don't have formal designations as endangered species, but fisheries-management measures are in play in the U.S. and in other areas of the world, especially Australia. That said, in most areas of the world there aren't fisheries-management measures in effect, or [they're not] enforced, and there are a lot of cheaters out there.
What do the fisheries managers do to protect sharks?
Managers implement restrictions on killing specific species, like great white sharks, in different ways. They can order fishermen to reduce the number of hooks or the sizes of nets, limit the sizes of catches, or limit fishing in certain areas in certain times of the year.
Great white sharks are generally not being killed as targeted fisheries; they're more commonly caught as bycatch on longlines or in nets.
There must be an equilibrium that doesn't put fishermen out of business, but also doesn't decimate the animals. It's a delicate balance. But sharks in general are still in trouble. (See "What Ate a 9-Foot Great White Shark? Another Great White?")
So what should people do to stay safe from shark attacks?
Attacks can be reduced by being smart about where you go into the water. You shouldn't ever anticipate 100 percent safety; you should understand that there's certain risk we accept [when we enter any] wilderness.
It's also a good idea to avoid going into the water at night, avoid wearing shiny metal that may look like fish scales, and stay away from sandbars and areas that drop off steeply.