A team of conservation divers has successfully removed and relocated nearly 11 years’ worth of coral growth from a decommissioned offshore fish farm pen that was towed into the Honokohau Small Boat Harbor on Hawaii island last week.

The operation, carried out by divers from the state Department of Land and Natural Resources Division of Aquatic Resources, The Nature Conservancy and Arizona State University, involved relocating hundreds of large, healthy native coral heads that had grown on the fish farm pipe ring, which was once used for raising kampachi — yellowtail or amberjack — in teepeelike structures. Four of the fish pens are still in operation and remain visible just off a runway at Ellison Onizuka Kona International Airport.

“Essentially, this pen has been in the water for eleven years, since 2013, and in that time, just natural recruitment of coral has happened to the point that now it’s time to take the pen out of the water. And there’s a whole, you know, eleven years’ worth of coral on the pen,” Julia Rose, the coral restoration program manager for TNC, said in a statement.

The partnership between these organizations has been working together for the past couple of years to build capacity for coral restoration and emergency response.

“Opportunities like this are actually really valuable, because the amount of time and effort and money that it would take to grow eleven years’ worth of coral that’s on these offshore pens is huge,” Rose said. “Any amount of coral that we can save from these pens today is so valuable. It’s the biggest bang for the buck that you can get.”

The coral removal process, which took three days, was complex but well orchestrated. Corals on top of the pipe were not recovered, as prolonged exposure to air kills them, but most of the corals below the water were removed using chisels and hammers.

These corals sank to the bottom of the harbor, where divers collected them in milk crates that were then lifted onto boats. Larger coral heads were carefully placed into water-filled coolers, while smaller ones were bubble-wrapped and placed in separate coolers.

“These structures are fantastic areas for these corals to settle on — great in the short run, but in the long run they need a proper reef home to survive. This is one of the largest mature colony collections that I’ve ever heard of on Hawaii island,” said Zachary Craig, the DAR Coral Restoration Coordinator on Hawaii island.

Once collected, the larger corals were transported by boat back to the reef, just inshore of the fish pens, where they were gently lowered to the ocean floor by divers. The smaller corals were taken to a new coral nursery at the National Energy Laboratory of Hawai‘i.

“In the nursery we can give them a kind of an intensive care unit for those corals that we’re rescuing and know that we’re giving them the absolute best conditions. We can also use that nursery to do other types of research to address the causes of coral stress,” said Dr. Grace Klinges, ASU restoration scientist.

The ‘Ako‘ako‘a Coral Restoration Nursery, which opened in May, is the first large, land-based coral nursery on Hawaii island and is believed to be the largest of its kind in the Pacific.

The dive teams collected hundreds of healthy coral colonies. Klinges said, “It’s great to be responding to something in a positive way where, you know, these corals would die otherwise. We think that we can save a fair number of them by working together. This is such a massive effort. I don’t think we even knew how big it was going to be until we got in the water and saw it. But I think we’ve made a monumental impact. The coral that we’ve been able to move to the nursery so far, they’re doing pretty well, and we hope they’ll continue to thrive over there.”

The corals that were returned to the ocean will be affixed to existing reef structures this week using a special marine epoxy.

Blue Ocean Mariculture, the company operating the kampachi aquaculture farm, partnered with the conservation team for this initiative.

“We are deeply committed to the health and resilience of Hawaii’s marine ecosystems, so we’re honored to partner with the DLNR and the other partners on this coral reef restoration initiative,” CEO Dick Jones said. “By providing reef samples from our net pens off the Kona Coast, we can help support the regeneration of vital species in our coral reefs, reinforcing both environmental sustainability and the balance of Hawaii’s coastal waters. This col­laboration is a natural extension of our team’s dedication to Hawaii’s ocean ecosystems and to preserving their vitality for future generations.”

“Our offshore team is on the open ocean every day, witnessing firsthand how marine life, including coral and other reef organisms, naturally establish on our net pens off the Kona Coast. Being able to share these samples for Hawaii’s reef restoration efforts is something we’re proud of, as it contributes directly to the work in regenerating healthy reef ecosystems,” said Tyler Korte, Blue Ocean Mariculture vice president of marine operations.