Monday, January 29, 2001
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Posted on: Monday, January 29, 2001

Manta rays off Kona live life of mystery

By Dan Nakaso
Advertiser Staff Writer

The 700-pound manta rays that glided slowly through the night waters off the Big Island were sometimes groped, grabbed and even ridden despite rules set up by scuba operators to protect them.

Scuba teacher Keller Laros swims with two manta rays off the Kona Coast. He catalogs their markings and names them.

Wendy Laros photo

The nightly opportunity to dive and swim with manta rays was one of the Big Island’s top attractions and was advertised around the world. At its peak, 10 boats and at least 100 divers gathered one March night in 1998 just 50 yards from shore.

But the tourists who paid around $100 each to see the animals up close and in the dark sometimes also got an unfortunate view of fishing hooks dangling from the mantas’ mouths or snagged on their fins.

Despite the manhandling from fishing lines and rogue snorkelers and divers who refused to obey the rules, the mantas kept returning to the Kona Surf Hotel at Keauhou Bay. They seemed to be drawn to the plankton, which in turn was attracted by the glare of the hotel’s lights.

Then the hotel closed June 30, and the lights went off. The number of mantas that came each night suddenly fell, sending a scare through the Big Island’s tourism and commercial scuba industry.

Today, scuba dive operators believe they’ve found the new gathering site of the manta rays about 15 miles north up the Kona Coast.

The spot, near the Kona Airport, sometimes goes by the names Garden Eel Cove, Garden Eels or Hoona Bay and is more isolated than the old location off the Kona Surf Hotel.

It’s not as popular with fishermen. And it’s much harder for unescorted snorkelers and divers to swim out from shore and disobey the commercial guidelines.

Mysterious species

While the new site might be easier on the manta rays, it doesn’t answer the questions of why they left Keauhou Bay in large numbers in the first place and what drew them to Hoona Bay, which doesn’t have the lights that attract plankton.

The answers may solve some of the mysteries of an enigmatic sea animal and help find a balance between commercial and environmental interests on the Big Island and the rest of Hawaii.

"It’s a very tantalizing mystery," said Bill Walsh, aquatic biologist for the state Department of Land and Natural Resources’ division of aquatic resources for West Hawaii.

"The problem with this species is next to nothing is known about it, its basic biology, its movement patterns, the basic information we would need to know whether there’s been an impact by divers," Walsh said. "We’re using them as an early warning system. And it’s in their best interest and our best interest that they stay healthy."

An estimated 60 manta rays appear to be roaming the Kona Coast. Their territory could be even larger, but there hasn’t been any research to find out.

"All I can do is put my hands up in the air and say, Who knows?’ " Walsh said.

Manta man

Most of what is known about the Kona Coast manta rays has not come from science, but rather from data collected by Keller Laros, a scuba instructor and dive guide whose family co-owns Jack’s Diving Locker in Kona.

Scientists from the state, University of Hawaii-Hilo and the UH Sea Grant Extension program all say Laros has kept the most detailed records of anyone. He’s catalogued the mantas by their markings and given them names from "Big Bertha" to "Cousteau" to "Faye Ray."

Laros did his first manta ray night dive off the Kona Surf Hotel in 1985 as a tourist from California. The only boat in the water that night belonged to Jack’s Diving Locker and only one manta ray appeared.

By the early 1990s, Laros had moved to Kona and scuba operators had yet to turn the manta ray dive into a major operation. But by the late 1990s, nearly all of the dozen dive companies along the Kona Coast were marketing the dive in some capacity. At only 20 feet, it was shallow and close to both the shore and harbor.

Even Mike Nakachi of Aloha Dive Co., who believes the rays were sometimes abused, felt he had to take customers to see the manta rays in order to compete.

"Everybody was doing it and there would regularly be seven or eight boats in the water," he said. "That dive is really overexploited. People were grabbing onto mantas and even some of the scuba operators were chasing them" with motorized underwater scooters.

In 1993, the scuba companies, with the help of The Ocean Recreation Council of Hawaii and the Professional Association of Diving Instructors’ Project AWARE, wrote guidelines for diving with the mantas. They say snorkelers need to stay on the surface and scuba divers must remain on the bottom to give the mantas room to maneuver.

They’ll be back

No one is supposed to harass or touch the rays, which can remove the mucous that protects them from infection. And scuba divers aren’t supposed to blow bubbles in their faces.

"We see the mantas with scuffs, and cuts and fishing hooks hanging from them," Laros said. "The manta ray has a tough life, so we tried to do whatever we could to help them."

Even before the Kona Surf Hotel closed, the number of mantas would often drop at certain times of the year for no obvious reason. Maybe it had something to do with mating or feeding or a change in water temperature.

But the last two Decembers have been especially slow, with sometimes only one or two manta rays appearing sporadically.

"I don’t know if it’s because of La Ni–a, El Ni–o, the plankton, the surf, or cooler water," Laros said. "It’s unfortunate that it happens when people are coming through at Christmas time."

Dinah Rodgers, who operates Manta Ray Divers of Hawaii with her husband Lee, believes the mantas have always been moving between Keauhou and Hoona bays.

"They’re just in search of food, plain and simple," she said.

At Hoona Bay, the yellow-and-blue Hawaiian cleaner wrasse fish have set up a cleaning station where they pick parasites off of the mantas. The dive site is also protected by Keahole Point, which may help divert plankton into the calm waters that are only 40 feet deep, Rodgers said.

Even with the scuba companies moving their operations to the new site, Nakachi believes the mantas are better off at Hoona Bay.

And he isn’t concerned about the recent drop in sightings.

"Maybe it’s just high surf, maybe it’s just the time of the year," he said. "All I know is that they go away. They’ll come back."

But Nakachi shares the concern of others that the mantas may already be sending an early warning.

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