BOSTON (AP) — A prominent shark researcher says smaller, younger great white sharks are being spotted in larger numbers off Cape Cod.

Massachusetts marine biologist Greg Skomal says the presence of juvenile sharks could be contributing to more encounters with humans because the young sharks tend to favor the large fish anglers also prize.

Cape Cod authorities, meanwhile, worry about what happens after Labor Day, when lifeguards leave.

The National Park Service says beach closures from shark sightings have more than doubled this year, and a 61-year-old New York man was severely injured after a shark bit his leg Aug. 15 off Cape Cod.

The International Shark Attack File in Florida says the attack is among 37 worldwide this year.