Study reveals tiger shark movements around Maui and Oahu

UH Mānoa researchers are using tracking devices to gain new insights into tiger shark movements in coastal waters around Maui and O'ahu. The ongoing study reveals their coastal habitat preferences

"We need to understand tiger shark movements in our coastal waters to gain a clearer comprehension of the circumstances bringing sharks and humans together," said Dr. Kim Holland, senior shark scientist at the Hawai'i Institute of Marine Biology.

In 2013, internationally recognized shark scientists Drs. Holland and Carl Meyer started a tiger shark tracking study in Maui waters, following a cluster of shark bite incidents around Maui in 2012 and 2013.

Twenty-four large tiger sharks were captured and fitted with tracking devices off Kīhei, Olowalu and Kahului, Maui. The tagging efforts are providing new insights into the coastal habitats most frequently visited by tiger sharks around Maui.

"We are seeing a strong preference for coastal shelf habitats shallower than 600 feet," said Dr. Meyer. "Although these sharks also roam far out into the open ocean, they are most frequently detected in the area between the coast and the 600-foot depth contour that is up to 10 miles offshore around Maui."

Around Maui, the coastal sites frequently visited by tiger sharks are directly offshore of popular surfing and swimming beaches.

Last month, the team of scientists began tagging large tiger sharks off the north shore of O'ahu to determine whether similar patterns of behavior occur around other Hawaiian Islands.

"We are tracking tiger sharks around O'ahu and Maui, simultaneously, so that we can have the clearest possible comparison of tiger shark behavior between these two islands," said Dr. Holland. "Both O'ahu and Maui have high levels of recreational ocean use, yet Maui has a higher rate of shark bites. We are trying to determine why."

"We are seeing the exact same depth preferences around O'ahu, but the most frequently used sites don't line up with popular swimming and surfing sites to the extent that they do around Maui," added Dr. Holland, who also cautioned that the O'ahu data in particular are "very preliminary."