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Two people were bitten by sharks off the coast of North Carolina this weekend, bringing the number of shark attacks in the state over the past three weeks to five. While some have speculated that shark fishing in the area is responsible for this uptick in the number of bloody encounters, others say the reasons for the attacks are probably a bit more complicated than that.

"It's not a certain thing that makes this happen," said George Burgess, director of the International Shark Attack File at the University of Florida's Florida Museum of Natural History. "It's a perfect storm of factors."

Both shark attacks this weekend occurred off North Carolina's Outer Banks, a 200-mile-long (320 kilometers) string of barrier islands that hugs the state's coast. Three attacks that occurred earlier this month took place just south of the Outer Banks, off the shores of Oak Island and Ocean Isle Beach. All of the victims have survived, though with injuries. [How to Avoid a Shark Attack]

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Related: Shark Attacks on Rise on North Carolina Coast

Many of the reports describing two attacks that occurred off Oak Island on June 14 mention that the victims were swimming near fishing piers where fishermen were chumming, or baiting, the water to attract fish. "Fishing off a beach where there are swimmers and surfers makes for a really bad mix," Burgess told LiveScience.

But there are other factors as well, Burgess said:

Parts of North Carolina have been abnormally dry or have experienced moderate drought conditions for several weeks. This means the salinity, or salt content, of ocean water close to shore is higher than usual. "With the exception of bull sharks, most all sharks prefer higher-salinity waters," Burgess said. The increased salt content could be bringing sharks closer to shore in greater numbers.

Large schools of herring have been spotted close to the North Carolina coast in recent weeks, Burgess said. This oily fish is a rich source of nutrients for sharks. "If you see fishes, seabirds diving, people fishing — these are all no-brainers. Get out of the water," Burgess said.

Other prey animals, such as baby sea turtles, can also encourage sharks to come close to shore. Many sea turtles have hatched along certain North Carolina beaches in recent weeks, and as they journey into the Atlantic waters, hungry sharks (particularly tiger sharks) are waiting just offshore, Burgess said.

The calendar and the weather also play big roles, in North Carolina and other coastal areas. Summer is in full swing, school's out, and folks are flocking to the beaches. "You put all these things together, and you've got a mix of humans and sharks in abundance," Burgess said

This is a condensed version of a report from LiveScience. Read the full report. Follow Elizabeth Palermo on Twitter. Follow Live Science on Twitter, Facebook and Google+.