The attack was the eighth near Maui and the thirteenth in Hawaiian waters this year—more than triple the 20-year average of about four unprovoked shark incidents each year.

Patrick Briney, the fisherman, was Hawaii's second shark attack fatality this year, following an August attack on a German snorkeler. Prior to 2013 there hadn't been a single fatal shark attack in Hawaii since 2004.

This year's attacks, on top of ten Hawaiian attacks last year, have people asking whether there's been a recent statistical anomaly or whether more shark attacks are Hawaii's new normal.

Yannis Papastamatiou, a marine biologist at the University of St. Andrews in Scotland, said it's nearly impossible to know what's behind the rise in attack numbers.

"The problem with shark bites