It's shark season on the East Coast.
Shark sightings have prompted authorities to temporarily close popular beaches in New England, New York and elsewhere this month. And 13 people have been bitten by sharks in Florida this year.
The Associated Press checked in with shark experts to see what's going on:
ARE SHARK SIGHTINGS ON THE RISE?
Researchers suggest this summer could be shaping up to a banner one for sightings, but it's too early to say for certain.
In Cape Cod, in Massachusetts, state marine biologist Gregory Skomal says great whites appear to have shown up earlier and in larger numbers. His team tagged its first shark in mid-June, and nine new ones have been tagged, up from three this time last year. It identified 141 last year and 80 the previous year. On Thursday, a great white shark was spotted off Nauset Beach in Orleans.
In South Carolina, state marine biologist Bryan Frazier says preliminary annual survey data of sandbar, blacktip and other shark species suggest the populations are continuing their steady rise after years of overfishing.
WHAT KINDS OF SHARKS ARE BEING SPOTTED?
In the Cape Cod area, researchers are focused on great white sharks, which tend to venture close to shore to eat seals. Other species, like blue and mako sharks, can be found farther out. Huge but harmless ocean sunfish have been mistaken for sharks.
In New York, where stretches of Coney Island's beaches were temporarily closed last week, authorities have suggested the multiple sharks spotted off the shore where likely basking sharks, which are largely harmless to humans. And in the Carolinas, large feeding frenzies of blacktip sharks, responsible for many attacks in southern Atlantic Ocean waters, have been observed more frequently than in past years.
WHAT'S DRIVING THE INCREASE IN SHARK SIGHTINGS?
Sharks have always prowled the waters near popular beaches, but we're more aware of how close they get because more people are sharing videos and photos of them on social media, says Cynthia Wigren, executive director of the Atlantic White Shark Conservancy, a Cape Cod-based nonprofit that recently launched a shark tracking app, Sharktivity.
Fishery management policies meant to help some shark populations recover from recreational and commercial overfishing during the 1980s and '90s also play a role, says Robert Hueter, director of the Center for Shark Research at Mote Marine Laboratory and Aquarium in Sarasota, Florida. Shark populations have generally been on the rise along the East Coast, though some species, like hammerheads and dusky sharks, still face significant challenges, he says.
HAVE THERE BEEN MORE SHARK ATTACKS?
No. This year there have been 22 confirmed unprovoked shark attacks in the U.S., none fatal, according to the International Shark Attack File, based at the Florida Museum of Natural History. There have been 36 confirmed attacks worldwide, three fatal. The International Shark Attack File's director, George Burgess, says those numbers put the U.S. and the world on pace to see fewer attacks than last year, when there were 59 in the U.S., one fatal, and 98 worldwide, six fatal.