For years, Hawaiʻi surfers and lifeguards have talked about “Sharktober,” a stretch of fall weeks when encounters with sharks seem to climb just as the first winter swells arrive. Now a detailed scientific analysis of decades of data confirms that shark bites in the islands really do spike in October, and that tiger sharks are driving much of the pattern. The same research is also beginning to explain why this happens, and how people can share the water more safely with one of the ocean’s top predators.
By tracing long term records of shark incidents alongside shark movements and life cycles, scientists have linked the October surge to tiger shark behavior near the main Hawaiian Islands. The work shows that the risk, while still very low in absolute terms, is not evenly spread through the year, and that understanding this seasonality can help everyone from casual swimmers to big wave surfers make more informed choices.
‘Sharktober’ goes from local lore to hard numbers
The idea that October is a riskier month in Hawaiʻi waters started as anecdote, passed along in beach parking lots and lifeguard towers. New University of Hawai research has now confirmed that Sharktober is real, documenting a clear rise in unprovoked bites during that month compared with the rest of the year, particularly from tiger sharks close to shore. In the latest analysis, scientists found that tiger shark bites account for a large share of the incidents that cluster in early fall, turning what was once a rumor into a statistically supported pattern backed by New University of data.
One summary of the work notes that of the 165 unprovoked shark bites recorded in Hawaiian waters between January 1995 and October 2024, 32 (20%) occurred in October alone, a concentration that would not be expected if incidents were spread evenly through the calendar. That means roughly one fifth of all recorded unprovoked bites in that 29 year span happened in a single month, even though October represents less than one twelfth of the year, a disparity highlighted in detail by researchers who examined those 165 cases and the 32 October events.
Decades of shark data reveal a seasonal pattern
To move beyond raw counts, scientists in Hawaii have pulled together more than 30 years of incident reports, tagging records and environmental data to see how shark behavior changes through the seasons. Carl Meyer, a marine biologist at the University of Hawai at Manoa’s Hawaii Institute of Marine Biology, analyzed three decades of records and found that tiger shark bites in particular rise sharply in October, a trend that lines up with what local water users have long suspected and that is now laid out in detail in a recent Carl Meyer overview.
State incident graphs tell a similar story, showing that there appears to be an increased risk of being bitten by a shark during certain months, in particular October through December, even after accounting for how many people are in the water. Those official charts, which track incidents around the main islands, underline that the October bump is not a one off fluke but a recurring feature of the record, with the state noting that There is a clear seasonal signal in the data.
Why October, and why tiger sharks?
The next question scientists tackled was why this spike happens in the first place, and the emerging answer points squarely at tiger shark biology. Study leader Professor Carl Meyer has explained that the October spike is real and statistically significant, but that the overall risk remains very low, and that the timing appears to line up closely with the pupping season when female tiger sharks move into shallower coastal waters to give birth. In his words, the pattern is not random but tracks “precisely with the pupping season,” a link that helps explain why tiger sharks are more likely to be near popular beaches at that time, as described in the Study he led.
Other researchers have echoed that view, noting that tiger sharks are more likely to be present in the nearshore waters of the main Hawaiian Islands during October, which naturally increases the chance of encounters with people. Scientists in Hawaii attribute the seasonality of bites to this combination of shark movements and human activity, with more large predators in the surf zone just as wave conditions and tourism keep crowds in the water, a dynamic that recent analyses of the Tiger presence around the Hawaiian Islands and the work by Scientists in Hawaii both emphasize.
From campus labs to beach warnings
The confirmation of Sharktober has not stayed confined to academic journals, it is already reshaping how officials talk to residents and visitors about ocean safety. New University of Hawai researchers have urged extra caution for people surfing, paddling or swimming in coastal areas during October, particularly in spots with a history of tiger shark activity, and that advice is now filtering into public messaging and signage that draws directly on the Sharktober findings.
Local news coverage has amplified that message, with reporters such as Cate Piper Labas explaining how the new analysis gives long standing community concerns a scientific backbone and how lifeguards are adjusting their briefings as a result. The research has also been summarized for a broader audience through accessible explainers that walk through the key points of the work, including the role of tiger sharks and the October spike, and that highlight how the New University of Hawai team and communicators like Cate Piper Labas are trying to balance awareness with reassurance.
Balancing risk, perception and conservation
Even with the October spike, scientists stress that the odds of any individual being bitten remain extremely small, especially compared with everyday hazards on land. Professor Carl Meyer has described the pattern as a “numbers game,” pointing out that more people in the water at the same time as more tiger sharks naturally raises the chance of rare encounters, but that the baseline risk is still very low compared with other activities, a perspective he has shared in interviews that unpack the Sharktober data.
At the same time, the new research is feeding into broader conversations about how to coexist with sharks without resorting to culls or other lethal measures that can damage marine ecosystems. Analysts have noted that understanding when and where tiger sharks are most likely to be near shore allows for targeted risk mitigation, from temporary closures after incidents to focused education campaigns in known hotspots, an approach that is reflected in both the technical summaries of the Key Points from the Hawaii work and in broader travel oriented explainers that translate those findings for visitors planning a trip to Hawaii.
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