KIHEI, Hawaii » A surge in shark attacks on Maui over the past year, including two fatal ones, hasn’t stopped people from surfing and swimming in the warm ocean waters that surround the Hawaiian Island.

But it has spurred sales of devices that claim to keep sharks away by emitting an electrical pulse.

"They just cannot make these things fast enough," said Hawaiian Island Surf & Sport owner Dennis O’Donnell, who keeps a waiting list for the products and sells out as soon as he’s restocked.

Users strap the devices to their ankles, wet suits or surfboards. Some are about the size of an oversize watch, others the size of a wallet. They range in price from $399 to $649.

Some shark experts say the devices may help in some cases, but it’s questionable whether they’ll repel large sharks.

The sales spike comes as there have been eight shark attacks in Maui waters last year. Statewide there were 14 attacks in 2013. There were 11 attacks in Hawaii in 2012 and three the year before.

In August a German tourist died a week after a shark bit off her arm. In December a man fishing on his kayak died after a shark bit his foot that was dangling in the water.

The last time anybody was killed by a shark in Hawaii waters was in 2004.

Sterling Kaya, owner of the Hono­lulu fishing supply store Hana Pa‘a Fishing Co., said he used a device once while spearfishing in the Marshall Islands.

Without it, sharks ate the catch he and his fellow fishermen strung to a float while they fished, Kaya said. But the sharks stayed away when they attached the device to their catch.

Carl Meyer, a shark researcher at the Hawaii Institute of Marine Biology, said the devices may reduce the risk of a shark bite but will not eliminate it, cautioning that no independent, peer-reviewed studies have been conducted on their effectiveness.

Burgess said the only people who would need one of the devices are those whose jobs put them regularly in direct contact with sharks.

Spear fishermen may also benefit as they are diving with bloody fish that can attract sharks. But there’s still a question of whether the electrical field released by the device will deter the fish they’re trying to spear, George Burgess, director of the Florida Program for Shark Research, said.

Burgess is also skeptical whether the devices will effectively deter large sharks that tend to be the types involved in fatal attacks on humans — like tiger, white or bull sharks.

Even so, he noted the odds of getting bitten by a shark are tiny. People are much more likely to drown or have a heart attack in the water than be attacked by a shark, he said.