WAIKAPU, Maui — Spear fishermen bagged more than 300 fish during yesterday's Roi Round-up Dive Tournament targeting three invasive species that threaten the health of Maui's reefs.

The event was organized by divers concerned about reef conservation and also served as a fundraiser for Lance Otsubo and Kimi Werner, who will represent the state at the U.S. National Spearfishing Championships in August off Malibu, Calif.

"We wanted to make a tournament to have fun and to raise money for the divers, but we didn't want to deplete the reefs, so we made it for invasive species," said organizer Darrell Tanaka. "Maui doesn't have the fish it used to have 10 to 20 years ago. A lot of divers are here because they want to give back to the reefs. They see the depletion and this is one of the ways we can bring the fish back."

Participants from Maui, O'ahu and Lana'i took aim at roi (blue-spotted grouper), ta'ape (blue-lined snapper) and to'au (black-tailed snapper). The three species were introduced to Hawaiian waters in the 1950s to boost declining stocks for sport fishing, but never caught on as popular eating fish. For one thing, roi is a high-risk fish for ciguatera poisoning.

All three are voracious predators that gorge on more desirable reef fish and compete for resources. Roi, which prey on juvenile parrotfish and surgeonfish, have become the dominant inshore predator in the main Hawaiian Islands. A University of Hawai'i study estimated that in a three-square-mile area off the Kona Coast, roi eat 99 tons of reef fish annually — the equivalent of 8.2 million fish.

Most of the 319 fish caught yesterday by 32 two-diver teams were roi, and since each roi consumes an average of 146 fish a year, the culling means more than 46,000 fish will be left on Maui's reefs annually.

None of yesterday's catch will reach the dinner table. The larger fish will be used by UH scientists for ciguatera research, including development of better detection kits for fishers. The remaining fish were given to an organic farm to be used as fertilizer.

Bryan Nakamoto, 35, and Dean Kawamura, 30, both of Wailuku, Maui, said they turned out for fun and to support Otsubo and Werner.

"There are a lot less fish nowadays. The sport has really blown up and there are more divers in the water," Nakamoto said. "I don't think these invasive species are helping."

Event organizer Tanaka and some of his buddies meet monthly to spear roi, selling the fish for $1.50 a pound to the Maui Ocean Center aquarium for fish food. Money from their efforts was used to buy some of the prizes awarded yesterday.

Also among the tournament sponsors was The Nature Conservancy, which used the occasion to survey participants about their fishing habits, encourage them to get involved in fishing-related issues and share information on reef conservation.

Evelyn Wight of the conservancy said the outreach is just as important as efforts to remove invasive species from the reefs.

Staff members from the state Division of Aquatic Resources conducted their own survey, asking fishers about their views on proposals to set catch limits and larger minimum sizes for goatfish, parrotfish and ulua.

Tournament winners were Tanaka and dive partner Lance Kimura for most fish (45) and smallest roi (58 grams); Dwayne DeSerres and Keoni Tamayo for largest fish (a 4.4-pound roi); Brendan Lee and Eric Barron for smallest ta'ape (92 grams); and Max Renigado and Gabe Johnson for smallest to'au (25 grams).

Two Roi Round-ups were held on Maui last year, with two more planned for this year. Tanaka is hoping the idea will spread to other islands.

He noted that Mayor Charmaine Tavares' staff has been a big help in organizing the events.

"Although the ocean is state jurisdiction, this shows the counties can have an effect on the reefs," he said.

The next Roi Round-up, a "Law Enforcement Shootout," will be held July 12 off Lahaina. For more information, call Tanaka at 808-575-2557 or e-mail roiroundup@gmail.com.