"If the economy's bad," Burgess explained, "people won't have money for vacations at the beach, and they won't be as likely to gas up their car to go surfing."
Our population continues to rise, however, as does our mobility.
"The more off the beaten path we go, the more likely shark attacks will occur," he said.
Globalization, tourism and population growth worldwide have all led to shark attacks in historically low-contact areas. These include places like Reunion Island, Papua New Guinea, Madagascar, Solomon Island and the small island of Diego Garcia in the Indian Ocean. The latter saw its first recorded shark attack in 2013.
Cage diving, where tour organizers attract sharks with bait, also can increase the chances for attack.
"We have previously analyzed data to see which sharks are hanging around shark tours with cage divers on Oahu, and one of the things we noticed was that you'd get a spike in how many tiger sharks are seen in October, which would match our predicted model that you're having an influx of big, pregnant females coming from the northwestern Hawaiian Islands," said Yannis Papastamatiou, a marine biologist with the Florida Museum of Natural History.