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When a 24-foot boat in Punaluu covered in mussels — and Japanese writing — a local family saw a tasty meal.

But state officials, who showed up on Christmas Eve to find many of the mussels eaten, saw a threat to Hawaii’s marine ecosystem.

The blue mussels, native to Japan, are considered an invasive species in Hawaii and the state’s Department of Land and Natural Resources is investigating the boat as likely debris from the March 2011 Japanese tsunami.

It’s the second boat in recent weeks to wash up in Hawaii carrying the sea critters. Last month, a broken up vessel also confirmed to be tsunami debris, .

The tsunami swept millions of tons of wreckage into the ocean and debris has been showing up on Hawaii’s coasts in recent months. For DLNR officials, a top concern is the impact that non-native species can have on the local ecosystem. And while officials are working to mitigate the threat, DLNR, the lead agency for debris cleanup, is still awaiting funding to help support efforts.

William Aila, chair of DLNR, said that the National Oceanic and Atmospheric Administration has promised $50,000, which will be matched by his department. He said that the funds were expected to be allocated any day. DLNR is also requesting $2 million from the Legislature, which would be available in July if approved.

There’s no estimate of how much the debris could end up costing the state. But Aila said that removing a vessel grounded in the Northwestern Hawaiian islands costs a minimum of $1 million. And while the small boats that have washed up on Oahu’s windward coast have been easy to manage, there could be significant costs if the mussels take up residence here.

Jono Blodgett, the aquatic species program leader at DLNR, said that the main concern is the threat to coral.

“If it does take hold, the concern is that they will just be able to populate at a fast rate and out compete some of our native species,” he said.

DLNR officials have protocols in place for containing invasive species that are found on debris. They are scraped off and frozen for a week to make sure they are dead, and if possible, vessels are decontaminated with a bleach solution, said Blodgett.

But if mussels escape into the ocean, officials have a more difficult problem.

Aila said that for the next several months, DLNR staff will be monitoring the waters where the boats have been found for evidence of the mussels, which will add additional costs for staff time.

“And if we find something, costs are going to go up,” he said.

Stopping the mussels from taking hold in Hawaii could be challenging.

“The mussels need to be attached to something to really be able to grow. If they were scraped off, generally they would just die,” said Blodgett. “But the concern is that when species are stressed out and about to die, they might release their eggs or sperm.”

The mussels thrive in Japan and are also common in the North and Mid-Atlantic regions, . And while they grow in abundance, the warmer waters around the Hawaiian islands could stop them.

“The good thing about here in Hawaii is that that these species come from Japan. They are a colder water species, so they have less of a chance of actually surviving in the warm water here,” said Blodgett. “So that will definitely help things.”

It’s not clear exactly how many of the mussels have been carried to Hawaii on the boats, in part because the Punaluu family ate many of the mussels on the vessel they found. The family flipped the boat over, carried it upstream to their home and scraped the mussels into a bucket, which was about half empty when Bloedgett arrived.

Despite public concern that tsunmai debris could carry radiation, DLNR says the risk that the mussels were contaminated is minimal. The meltdown of the Fukushima nuclear power plant in the days following the tsunami spewed radiation and prompted the Japanese government to evacuate thousands of residents. But Blodgett said that the boat was probably swept out to sea when the waves hit.

“The boat was probably sitting in the water in Japan,” he said. “So it would have been one of the first ones to be sucked out to sea before the reactors blew.”

The mussels are filter-feeding organisms, and for the past year and a half filtered clean, open ocean water, said Blodgett.

DLNR is working to find the owner of the boat in Japan. If it’s not claimed, or the owner doesn’t want it, then the Punaluu family gets to keep the boat. The remaining mussels, however, were confiscated.

What’s left of the Punaluu family’s bucket of mussels.

(Photo: Hawaii Department of Land and Natural Resources)