Two Honolulu hula supply store owners who insisted they were unaware of a state law barring the removal of rocks from beaches were fined $3,500 yesterday for taking as much as $20,000 worth of 'ili'ili stones from a Maui shoreline.

The state Board of Land and Natural Resources unanimously accepted a staff recommendation to punish Michael and Sylvia Kop for removing 16 five-gallon buckets of the small rocks from Waiehu Beach on May 29. The couple, who own the Hula Supply Center on South King Street, said they would appeal the administrative sanction.

The small, smooth stones are used in hula dances to provide a rhythmic sound much like castanets.

In testimony before the board voted, Michael Kop said he had gathered stones from Waiehu Beach since he was a child and has frequently done so in more recent years to sell at his store.

"I never felt I was stealing rocks from this beach," he told the board.

His wife said they did not know of the state law prohibiting the extraction of rocks, sand, coral and other natural material from beaches and submerged lands, other than small amounts for noncommercial use.

But the Kops also complained that there were no signs warning of the law, and that it is difficult to get information from the Department of Land and Natural Resources on obtaining a permit to remove rocks.

"We're admitting we took the rocks," she said, adding that she and her husband were trying to fulfill a demand for the stones for use in cultural ceremonies. "It's a service," she said. "It's strictly a service."

But board members were unsympathetic to the Kops' argument.

Samuel M. Gon III said it was "offensive" for the couple to couch a commercial enterprise as a cultural one. Robert Pacheco said the couple, as business owners, should have known what the law on removing rocks is.

And Jerry Edlao, a member from Maui, said he understood the cultural aspects of the Kops' argument but cited a broadening worry about the depletion of Hawai'i's environment. "Times are changing," he said. "More and more people are concerned about resources."

The case began May 29 when the couple placed their buckets on a Young Brothers cargo ship in Maui for shipment to O'ahu. Authorities were called by company personnel who had become attuned to people taking rocks from Maui after a case last year in which three O'ahu men attempted to transport trucks loaded with rocks on the Hawaii Superferry.

Conservation officers later estimated that each of the buckets held as many as 400 stones, and that their total value was as high as $20,000.

The fine includes $2,000 for the unauthorized taking of the rocks and $1,500 for administrative costs.