Fishing piers can be a magnet for sharks even when people aren't looking to land them because live bait is in the water and the pilings from the structure itself offer refuge for fish. There are also fish guts and blood from caught and cleaned fish that are sometimes tossed back into the water.
"That's going to attract fish and that's going to certainly attract sharks," North Carolina Division of Marine Fisheries Director Louis Daniel said. "If they get into the surf zone where the water is a little muddy and cloudy and there's dead fish parts floating around and they're gobbling it up," the sharks can get confused and bite a person.
Fishermen say they don't think they should be blamed or punished for the rare shark attacks, but local officials in Oak Island want a shark fishing ban to limit the food supply for sharks close to shore — at least through the popular Independence Day holiday weekend, town manager Tim Holloman said. It's not clear how a ban could be enforced, but could involve limiting the use of certain types of hooks, rigs and bait used for shark fishing.
Experts say swimming farther away from piers is a good idea, regardless of whether a shark fishing ban is in place. At Oak Island, two young people lost limbs in separate, life-threatening shark attacks within 90 minutes of each other on Sunday. One happened in the shadow of a fishing pier. The other was 2 miles away.
Both had been swimming about 20 yards offshore, in waist-deep water.
Virginia Beach, Virginia, and Myrtle Beach, South Carolina, are among popular destinations that have outlawed shark fishing from piers to try and better protect swimmers. Towns in Florida have also considered bans.
In North Carolina, it's legal to attract sharks by placing fish parts — also called chum — into a mesh laundry bag and hanging it off the side of a boat or pier, allowing the scent to attract sharks. But even without chum, virtually any structure in the water offers a place for fish to congregate, and that gives sharks a destination for hunting, said John Zardus, an associate professor of marine biology at The Citadel in Charleston, South Carolina.
"With their sensory system, they are able to tell there is structure and they know from experience that food is in that area," he said.
Last Sunday, Kiersten Yow, 12, of Asheboro, was swimming about 100 yards from Oak Island's Ocean Crest Pier when a shark attacked. She lost her left arm below the elbow and suffered leg injuries. Her parents said in a statement Tuesday she was in stable condition.
Nearly 90 minutes later, a shark bit off the left arm above the elbow of 16-year-old Hunter Treschel of Colorado Springs, Colorado. He was in good condition Wednesday at a Wilmington hospital, spokeswoman Carolyn Fisher said.
Officials do not know if they were attacked by the same shark.
The Ocean Crest Pier — near where the girl was attacked — allows shark fishing only at night, but forbids floating bags of chum, manager Steve Sanders said.
The town's other pier, the Oak Island Pier, is 2 miles from where the boy was attacked. That pier boasts the state's record-breaking tiger shark, a 1,150-pound monster caught there in 1966.
The Oak Island Pier allows shark fishing during its open hours but doesn't allow chumming, said operator Tommy Thomes. He said town officials would have to show him some evidence his pier is imperiling swimmers by attracting sharks.
"Until we get some other support than the town's opinion, no we would not" stop allowing shark fishing, Thomes said.
Shark fishing usually involves large hooks, strong steel fishing rigs and bloody cut bait, such as the head of another large fish.
It's unclear whether shark fishing bans are effective. Beth Firchau of the Virginia Aquarium and Marine Science Center said she doesn't know whether shark fishing increases the likelihood of an attack or of any marine scientists studying the bans.
But, she said, "we know that the act of fishing is all focused on attracting animals to your bait. And so if you're actively fishing in an area where people are swimming, one plus one equals two."
Virginia has had just five attacks since 1837, with the only fatality coming when a 10-year-old boy was attacked south of Virginia Beach in 2001. After that deadly attack, Virginia Beach expanded its ban on shark fishing or chumming to include all of the city's waters to within 500 feet of shore.
Only five shark bites have been reported in South Carolina waters in 2014, and there were just four in North Carolina last year, part of a gradual increase in recent years, according to the International Shark Attack File report compiled by the Florida Museum of Natural History and the University of Florida.