Weather may have contributed to shark attacks

Shark victim arrives in Virginia from the Outer Banks

AVON, North Carolina (CNN) -- A light northeast wind along North Carolina's Outer Banks that pushed warmer, clearer waters closer to shore may have been a factor in a Labor Day shark attack that killed a man and critically injured his girlfriend, a marine expert said Wednesday.

The same conditions also may have been present about 100 miles to the north, where a 10-year-old boy was killed in a shark attack Saturday, said David Griffin, director of the North Carolina Aquarium on Roanoke Island. He speculated the conditions may have influenced shark activity.

"The winds move warmer, clearer water on shore. When that happens, the food sources -- the bait fish -- move closer in shore and the sharks follow the bait fish in," he said.

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Sergei Zaloukaev, 27, died soon after he and his companion, Natalia Slobodskaya, 23, were attacked in the waters off Avon, near Cape Hatteras, on Monday. The two, Russian nationals living in northern Virginia, were with five friends from the Washington area on vacation and had been swimming near a sandbar about 20 feet from shore.

Both suffered multiple large bites. Slobodskaya, whose left foot was severed in the attack, was in critical but stable condition Wednesday at a Norfolk, Virginia hospital, and her doctors said she was making progress in her recovery.

Farther north, in Virginia Beach, Virginia, a shark killed 10-year-old David Peltier on Saturday.

The boy was swimming with his father and his brothers on a sandbar, about 50 yards offshore, when a shark attacked in 4-foot-deep waters. His left femoral artery was severed, and he bled to death.

Feeding frenzy

Both attacks happened in the evening, an active time for sharks.

"Sharks are primarily nocturnal feeders," said Griffin. "Therefore the interactions [with people] at dawn and dusk may be the greatest."

While the evening activity would not affect how intensely a shark bites its prey, he said, the excitement when one shark finds food often causes other sharks to draw near. He said the movement of hands and feet in the water -- including splashing or swimming -- stimulates sharks' "feeding response."

Griffin said it was possible that more than one shark -- even more than one species of shark -- may have been involved in either or both of the attacks. "Sharks are not separatists. They will intermingle with other species," he said.

National Park Service spokeswoman Mary Doll said investigators were assembling shark experts to help determine whether more than one shark was involved.

The medical examiner had not found any teeth in the victims' wounds, making identification of the type of shark more difficult, she said. Bull sharks, hammer heads, tiger sharks, reef sharks and blue sharks frequent the area, Griffin said.

Beaches open Wednesday

Beaches along the Outer Banks area in North Carolina were open Wednesday, Doll said, after a morning flyover by the state's Civil Air Patrol spotted only two sharks along the 90-mile stretch from Cape Hatteras to the Virginia border.

A second flyover was planned for the early part of Wednesday evening, she said. County officials flew over the area Tuesday but spotted nothing unusual in the water.

So far this year, there have been a total of 52 worldwide shark attacks -- including Monday's two victims -- reported to the International Shark Attack File, based at the University of Florida in Gainesville, Florida. Of those attacks, 41 have been in the United States, including 29 in Florida.

Last year, there were 79 shark attacks worldwide, according to the center's Web site, which said the annual average of shark attacks during the 1990s was 54.