"Nookie is going on too," he said. "Sharks tend to mate during this time."
Both he and Burkholder remarked that the migration is happening later this year.
"Sharks are temperature dependent. The ups and downs of global climate change can affect water temps," Burgess explained.
Humans, he said, are no different, since we can tolerate some climates more so than others.
"That's why a bunch of people live in Florida, but not at the North Pole," he deadpanned.
The later migration coincided perfectly with this year's Spring Break, when numerous college students head to beach towns to relax and party. Florida is the most dangerous state in the United States, in terms of shark attacks, and such encounters are at a 12-year high now.
The sharks in the swarm are known to bite people, but usually these are "hit and run" attacks, Burgess said. Researchers actually document these attacks to track the movement of the big shark congregation as it moves northward.
The good news is that "humans are not on the sharks' normal menu," Burkholder said, adding that it's "almost always a case of mistaken identity, especially in areas where the water is murky or near dusk or dawn, where the shark bites a swimmer thinking they are their normal fish prey."