KAILUA, KONA, Hawai'i — A group of scientists and an offshore aquaculture businessman are proposing a two-year project to restore 'opihi populations by creating offshore farms for the small limpets native to Hawai'i.

The Islands' 'opihi stocks have been depleted by overharvesting, with some saying the mollusk is at risk of extinction. State law restricts the taking of 'opihi, but critics say the rules are weak and aren't stopping stocks from declining.

Dale Sarver, the president of Deep Blue Research LLC, a company specializing in offshore aquaculture, says some aspects of 'opihi reproductive biology make the species a good candidate for hatchery production in large quantities.

Sarver and a group of biologists hope to breed 'opihi on the Kona Coast with the goal of boosting populations to the point where the mollusk may survive without human help.

"It is our responsibility to bring back populations of 'opihi to their natural levels," he said. " 'Opihi are important to all Hawaiians and Hawai'i itself. We have the tools and now we need to try."

Sarver, who has experience growing 'opihi varieties like the black foot, yellow foot and koele, is working with scientists from the University of Hawai'i and other institutions.

They are seeking funding to study 'opihi populations throughout the main Islands because this would help scientists employ management and stocking strategies.

They also are seeking endorsements and support from the community.

One measure that would help is an amendment to state House legislation seeking to expand the state's aquaculture industry by encouraging the growing of shellfish such as clams, oysters and 'opihi. The amendment appropriates $168,600 to fund the hatchery project's salaries, rent, materials, supplies and overhead costs.

The scientists also are calling for stronger restrictions on 'opihi harvesting.

The current rule allows 'opihi collection all year and calls for harvested limpets to be 1.25 inches across the shell, or the meat at least a half-inch wide.

But Sarver said 1.25 inches is very close to the size of 'opihi when they first reproduce.

"They hardly get a chance to start spawning before they are harvested," Sarver said.

Many also are harvested below the legal minimum size and before they have had the chance to reproduce.

"It's time we increase the legal minimum size before there are no 'opihi left," Sarver said.