Do more tiger shark bites occur in Hawaii during the month of October?
They do, according to a new study by the University of Hawaii at Manoa, which confirmed there is, indeed, a statistically significant spike in shark bite incidents in local waters every October.
The study, recently published in “Frontiers in Marine Science,” analyzes 30 years of Hawaii-specific data from 1995 to 2024.
It found that about 20% of all recorded bites occurred in October, likely due to seasonal movements and reproductive
cycles.
“The October spike is real and statistically significant, but the overall risk remains very low,” said Carl Meyer, lead researcher and professor at UH’s Hawaii’s Institute of Marine Biology, in a statement. “This pattern appears to be driven by tiger shark biology, not by more people being in the water.”
Meyer had been interested in answering this question for at least a decade, and with 10 more years of data, felt he could now conduct a robust, statistical
analysis on it.
More than just hearsay, local knowledge or urban myth, the “Sharktober” phenomenon is now backed by data.
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“You can see it in aggregate over 30 years,” he said. “So, roughly every other October has at least one shark bite, and you don’t see anything like that with the other calendar months.”
Additionally, October is when multiple shark bites occurred within the same month, which is unusual.
The reasons for the uptick are likely linked to tiger shark pupping season, and the migration of female tiger sharks from the Northwestern Hawaiian Islands to the main isles.
Tiger sharks, or Galeocerdo cuvier, give birth from September to November, but October is peak pupping time, according to Meyer.
The main Hawaiian Islands are very likely their pupping grounds, as tracking data has shown a regular migration of females from the northwest during that time.
This helps explain why there is a temporary bump in the number of large, adult female tiger sharks in nearshore habitats, and why more are seen during ecotourism activities on Oahu’s North Shore in October.
After giving birth to a large litter, many female tiger sharks are also depleted — or very hungry — and actively foraging to replenish their energy reserves.
This larger presence increases the probability of encounters with people in October, and is basically a numbers game, Meyers said.
In Hawaii, researchers estimated an average of three to four shark bites per year.
The Hawaii Department of Land and Natural Resources recorded a total of four shark bites in the state last year, five in 2024, and eight in 2023.
A Big Island diver was bitten in December while attempting to disentangle a blacktip reef shark from fishing gear.
On Kauai, lifeguard Chance Martin was bitten by a shark in November while surfing solo while off-duty near “Pine Trees” at Hanalei Bay, severing a major artery in his leg. Martin survived, but is expected to face a long recovery.
The other incidents occurred on Oahu, at Makapuu in July, and in Haleiwa during a swimming with sharks activity in January. DLNR considered the latter a provoked incident.
In 2023, two shark bites involving surfers occurred in October, at Kuau Bay on Maui, and Hanalei Bay on Kauai.
Researchers said the risks of getting bitten by a shark are still statistically rare, even in October.
“So we’re seeing this sort of pattern emerge where you can have significantly elevated risk, but the absolute risk still remains very low,” said Meyer. “Understanding when risk is slightly elevated helps people make informed choices, not fearful ones.”
Ocean users should be aware that tiger sharks are more likely to be present in nearshore waters of main isles in October, and take extra caution, particularly for high-risk, solo activities such as surfing or swimming.
Meyer said for him, personally, it’s not a great enough risk to stop surfing in October. But one can reduce risks by surfing with others and maintaining situational awareness.
“The takeaway message is always, when we enter the ocean, we enter a wilderness area and it’s the natural habitat of those predators,” he said. “They don’t have a choice. That’s where they live. We choose to go and play in the ocean and so, we’re making informed decisions about our risks.”