Many of the tiger sharks roaming around our waters these days are mature females that migrated from the northwestern Hawaiian islands, researchers have found. 

About a fourth of the mature female sharks based in those remote coral atolls make the 1,500-mile trek down to the main Hawaiian islands in the late summer and fall, likely to give birth to pups, new research from the University of Hawaii at Manoa and University of Florida shows.

Researchers Yannis Papastamatiou, of UF, and Carl Meyer, a marine biologist at UHM, point to links between the sharks’ migration and pupping patterns. Tiger sharks are known to pup between September and early November, and the increased risk of shark bites during that season is well-documented. About a third of mature female sharks are pregnant every fall, according to Papastamatiou.

Still, the researchers caution the public from attributing the recent spike in shark bites to those trends, citing a range of behavioral factors. (Meyer is set to head an upcoming two-year Department of Land and Natural Resources study on tiger shark movements in the islands.)

The university research also further debunks the long-standing myth that tiger sharks are territorial, sticking to specific coves and bays. The sharks rarely hang around the same area for more than a few weeks, data show.

As noted in the press release,

The territoriality hypothesis led to culls during the 1960s and ‘70s under the belief that killing sharks in locations where people had been hurt meant killing the shark that had attacked them, eliminating a “problem” shark. 

Papastamatiou said such culls don’t reduce the number of attacks. 

Some tiger sharks are transient while others are resident. Tiger sharks can be found in waters around the main Hawaiian islands throughout the year. 

Photo: A tiger shark. (Courtesy of thievingjoker via Flickr)

— Alia Wong