October is when swimmers and surfers in Hawaii appear to be at greater risk of getting bitten by a shark.

Based on the statistically-bolstered risk, state Department of Land and Natural Resources Division of Aquatics Resources Administrator Bruce Anderson is recommending that beachgoers exercise a little more caution.

In a news release, the land department said in 2012 there were two bites in October.

In October 2013, there were three, then four in October 2014, and three in October 2015.

“The three bites last October were all around Oahu, off different coasts of the island, and took place over a span of 20 days,” Anderson said. Two were very serious, with victims losing part of a limb. It was an unprecedented spike, but like nearly every spike in shark incidents, the most likely explanation is just chance.”

Another possible explanation, according University of Hawaii research funded by the land department, is that sharks give birth in the fall.

About 25 percent of the female tiger sharks in the Northwestern Hawaiian Islands migrate to the main islands in the fall to give birth, the state land department reported.

The increased number of sharks in near-shore waters, combined with their need to feed to replenish lost energy stores, may increase the likelihood of a bad encounter with a human.

State land department data, from 1980 through 2015, show that there were 122 unprovoked shark bites in Hawaiian waters.

Twenty-six of those, or 21 per cent, occurred during the month of October, the state land department said, citing with well-known victims such as Michael Coots, who lost his lower right leg in a shark attack while bodyboarding at Kauai’s Majors Bay; and Bethany Hamilton who lost her left arm just below the shoulder in 2003 in a shark attack while at Tunnels, a surf spot on Kauai’s North Shore.

So far, no October bite has been fatal.

“October is the month with the greatest number of shark bites,” said Anderson. “We recommend ocean users exercise a little more caution this month especially, and also through the end of the year. The chance of being bitten by a shark in Hawaiian waters is always extremely small, but does increase a bit during this time frame.”

“The best thing ocean users can do to minimize their risk of shark bites is to utilize beaches with lifeguards, stay near other people, and don’t go too far from shore. Also, avoid murky water and areas near stream mouths.”

More safety tips can be found at the Division’s shark web site, hawaiisharks.org.