Tracking tiger sharks: Key research findings released

Tracking tiger sharks: key research findings released
Published: Nov. 21, 2014 at 1:47 AM HST|Updated: Nov. 21, 2014 at 1:55 PM HST
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UH/ Mark Royer
UH/ Mark Royer

KAHULUI, MAUI (HawaiiNewsNow) - An unprecedented spike in shark attacks over the past two years prompted state officials to fund a study to tag and track the movement of tiger sharks in the waters off Maui.

Lead researcher, Dr. Carl Meyer from the UH Hawai'i Institute of Marine Biology, shared his findings for the first time in a public presentation at Chaminade University Thursday night.

The key question researchers set out to answer is: whether recent shark bite incidents are best explained by pure chance and because there is an increasing number of people in the water -- or whether there is a specific reason sharks are behaving the way they are around Maui. At the time the study was funded, there had been eight attacks statewide and 10 the year before -- despite a prior statewide average of only three to four attacks every year. There have been three so far this year.

Last October when Dr. Meyer launched his project, researchers were operating under the belief that sharks were wide-ranging animals that don't spend a lot of time in certain spots -- but that's no longer the case.

"We are seeing a strong preference for coastal shelf habitats shallower than 600 ft," 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 ft depth contour which is up to 10 miles offshore around Maui."

Dr. Meyer, a marine biologist with the University of Hawai'i, and his team successfully equipped 35 tiger sharks with tracking devices to study their natural behavior and movement patterns with the intent to clarify the circumstances that are bringing sharks and humans together and resulting in shark bites.

24 large tiger sharks were captured and fitted off Kihei, Olowalu and Kahului, Maui. What Dr. Meyer's team discovered is on Maui, the coastal sites frequently visited by tiger sharks are directly offshore of popular surfing and swimming beaches.

Scientists began tagging large tiger sharks off the north shore of O'ahu last month to determine whether similar patterns of behavior occur outside of Maui.

Dr. Meyer says the data is still very preliminary but researchers are observing the same depth preferences around O'ahu, but says those most-frequently used sites don't line up with popular swimming and surfing sites the way they do around Maui.

The State of Hawaii's Department of Land and Natural Resources (DLNR) spent $186,000 to fund the movements of tiger sharks caught and released around Maui. DLNR officials say they plan to use the results of the study to guide future decisions regarding management of shark populations statewide.

Maui tiger shark tracks are available online, and starting Thursday, O'ahu tiger shark tracks can also be followed on the Pacific Islands Ocean Observing System (PacIOOS) website.

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