A scientific study of shark-cage dive tours in Hawai'i indicates they pose little risk to public safety, largely because they operate at least three miles offshore and are frequented by Galapagos and sandbar sharks, two species rarely involved in attacks on humans.

Hawai'i Institute of Marine Biology researchers, using acoustic telemetry to track the movements of sharks tagged during the tours, found the animals overwhelmingly stay far out to sea and don't follow tour boats back to shore.

"When it comes to offshore caged shark-diving tours, there is no evidence of any risk to nearshore recreational users," marine scientist Carl Meyer said.

The tours have been operating off O'ahu's North Shore since 2001, capitalizing on a pre-existing phenomenon of sharks congregating around crab-fishing boats that have been using the same area for more than 40 years. The small crab fishery already has conditioned sharks to look for bait discarded from traps set at depths of 200 to 400 feet, Meyer said.

The newly released research also notes that stimuli from inshore recreational activities, such as a surfer paddling on a surfboard, are substantially different from the conditioning stimuli associated with the tour operations, namely the sound of boat engines. Therefore, the tours are unlikely to stimulate a conditioned feeding response in sharks, the study said.

"If these shark tours were a real problem, we would have seen it manifested by now in an increase in attacks," Meyer said.

Shark-diving tours became the subject of renewed controversy when a company planned to launch an operation off Maunalua Bay in Hawai'i Kai. Following community opposition, the company, Shark Discovery Hawaii, dropped its plans.

On April 28 the Hawai'i Kai Neighborhood Board passed a resolution to support a ban on commercial shark tours in Maunalua Bay and statewide.

The Hawai'i Kai controversy has prompted several state legislators to consider introducing a bill to ban shark-dive operations in Hawai'i. During a public meeting on the subject at the Capitol last night, few disputed Meyer's research findings, but representatives of eight scientific and public interest organizations present said they remain unconvinced that commercial shark tours are a favorable enterprise in Hawai'i waters.

"It's amazing to see them dangling things off the sides of the boats and feeding these sharks," said Stuart Coleman, Hawai'i coordinator of the Surfrider Foundation. "You cannot tell me that's healthy and doesn't pose a threat to the people on the boat and to the sharks themselves."

Coleman pointed out that it is illegal to bait or chum for sharks up to 200 miles out to sea.

"The shark tour operators can say, 'Well, we don't do that,' or 'We do just a little bit.' But we all know, based on common sense, that to attract these sharks they have to bait the water."

Billy Robello, with Save Our Surf, showed video of shark tours in which tourists are seen baiting sharks with meat tied to lines and coaxing the animals to snap at the food.

"That's not educational," Robello said. "A shark shouldn't be treated in this manner."

'REALITY AND FACTS'

Earlier yesterday, Stefanie Brendl, owner of Hawaii Shark Encounters, which operates out of Hale'iwa, yesterday welcomed the scientific findings, which she hopes will counter "the emotional mudslinging" targeting the tours.

"I'm really happy that it's coming from a neutral direction from a knowledgeable expert who has the data, so that we're actually starting to look at some reality and facts instead of all those gut feelings people might have about sharks," she said. "It's good to get a rational discussion. Decisions have to be made based on looking at the facts and not by who is shouting the loudest."

Australia and South Africa license shark-cage diving operators, and Florida and Hawai'i have banned shark feeding in state waters. Shark feeding, except for fishing, is banned in federal waters.

Hawaii Shark Encounters and North Shore Shark Adventures said they do not engage in shark feeding, although Meyer's description of the operations noted that a small amount of fish scraps is used to attract sharks close to the cage for easy viewing and photography.

Meyer said keeping the shark-diving tours outside state waters remains prudent.

"It's probably the most important factor. It creates a buffer and keeps these activities offshore," he said before last night's meeting.

Similar operations in the Caribbean and some other locations are conducted on reefs without the protection of cages, and there have been instances in which participants have been injured or killed by sharks.

TRANSMITTERS USED

The Hawai'i Institute of Marine Biology research involved a two-year study of sharks at the tour sites and analysis of four years of log book records kept by the two companies.

Meyer's team implanted transmitters on sharks at the tour sites and set up listening arrays at the sites and at a buoy 20 miles out to sea, as well as at adjacent nearshore areas. During the two-year study period, the receivers recorded more than 550,000 detections of 36 tagged sharks at the shark-cage diving sites and five miles off Waimea Bay, mostly at depths of 300 to 500 feet. During that same period, the nearshore arrays picked up only 21 detections of three sharks.

"Their primary center of activity, based on our receiver data, is the deeper ledges around the island, and from there they have some presence much deeper offshore and a minor presence in nearshore areas," Meyer said.

The sharks' movement patterns also were consistent with patterns seen at other areas of Hawai'i where there are no shark-diving tours, he said.

Galapagos and sandbar sharks comprise more than 98 percent of the sharks frequenting the caged-diving sites, the study found. Worldwide, since records have been kept, there have been only five confirmed unprovoked attacks attributed to sandbar sharks and a single attack attributed to a Galapagos shark, according to the International Shark Attack File.

Although potentially dangerous tiger sharks and hammerheads are occasional visitors to the tour sites, and a white shark once cruised by, "There is no evidence that the rate of shark attacks along the adjacent coast has increased significantly since the advent of shark-cage diving operations in 2001," the study noted.

Aside from public safety concerns, caged shark-diving tours are opposed on philosophical grounds that the activity alters the natural behavior of sharks.

Meyer said humans already are doing that in myriad ways. "Bear in mind that in populated areas, we do all kinds of things every day that influence marine and terrestrial ecosystems. We fish, we put bait into the water for fishing that may attract sharks," he said.

"Our studies and other research indicate the ecological impacts are probably on the low side."