Learn & Explore/Programs & Initiatives/Sportfish Restoration Fund/Artificial Reefs

Artificial Reefs

Permanent seafloor structures that enhance marine habitat and support sustainable fisheries in Hawai‘i.

Artificial Reefs

The Hawai‘i Division of Aquatic Resources (DAR) Artificial Reef Program enhances marine habitat by placing environmentally appropriate structures on the seafloor. These structures create habitat for reef‑associated and bottomfish species in areas where natural relief is limited, supporting sustainable fisheries and fishing opportunities statewide.

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What Are Artificial Reefs?

Artificial reefs are permanent seafloor structures designed to mimic natural reef habitat. They increase habitat complexity and provide shelter, feeding areas, and spawning grounds for fish and invertebrates.

Artificial reefs are placed directly on the seafloor and are intended to benefit reef‑associated and bottom‑dwelling species.

Program History

In 1957, the Territory of Hawai‘i began exploring the use of artificial structures to improve fisheries in areas with limited natural habitat.

The State’s first artificial reef was installed in 1961 at Maunalua Bay, off Kahala, O‘ahu (approximately 74 acres). Additional deployments followed:

1963

Keawakapu, Maui (54 acres)

Wai‘anae, O‘ahu(141acres)

1972

Kualoa, O‘ahu (1,727 acres)

1986

‘Ewa Deepwater Artificial Reef(31 acres)

Program Benefits

Artificial reefs provide ecological and fisheries benefits, including:

  • Enhanced habitat in areas with limited natural structure
  • Increased fish biomass, often up to 20 times greater than pre‑deployment conditions
  • Increased species diversity, commonly up to five times greater
  • Improved fishing opportunities for reef and bottomfish species
  • Reduced pressure on natural reef ecosystems
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Materials Used

Materials used in artificial reef construction have evolved over time to improve durability and environmental performance.

Earlier Materials

1961–1963

Decommissioned car bodies

1964–1985

Concrete pipe, barges, and a decommissioned minesweeper

Transitional Materials

1985–1991

Concrete and tire modules, derelict concrete material, barges, and large truck tires

Current Materials

1991–Present

  • Concrete z‑modules (primary material)
  • Barges
  • Derelict concrete material
  • Select small vessels

All materials are reviewed to ensure they are stable, durable, and suitable for long‑term marine use.

About Concrete Z‑Modules

Concrete z‑modules are the primary component of modern artificial reef deployments in Hawai‘i.

  • Dimensions: 4 feet × 8 feet
  • Elevated on 12‑inch legs on opposing ends
  • Weight: approximately 2,800 pounds
  • Reinforced with 90 linear feet of ½‑inch rebar 
  • Approximate cost: $130 per module

A typical deployment includes 1,300–1,800 modules, with an average project cost of approximately $230,000, including tug and barge services. All modules are made using donated concrete, reducing overall program costs.

Other Materials and Partnerships

Much of the material used in artificial reef construction is donated by private companies and state or federal agencies, most commonly the U.S. Coast Guard and U.S. Navy.

These donations allow DAR to use non‑state funds as match for the Federal Sport Fish Restoration (Dingle‑Johnson) Program, helping support reef construction while limiting reliance on state funding.

Permitting and Environmental Review

Artificial reef projects require authorization from the U.S. Army Corps of Engineers, the lead federal agency responsible for artificial reef permitting under the National Fishing Enhancement Act of 1984.

Projects also undergo:

  • Coastal Zone Management federal consistency review
  • Department of Health water quality certification
  • Required environmental review under state and federal law

These processes ensure artificial reefs are designed and deployed responsibly.

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Artificial Reef Locations

PDF maps and coordinates for artificial reef sites are available for download.

O‘ahu

  • ‘Ewa
  • Kualoa
  • Maunalua
  • Wai‘anae

Maui

  • Keawakapu

(File sizes range from approximately 408 KB to 2.8 MB.)

Looking Ahead

Long‑term program goals include:

  • Expanding existing artificial reef sites
  • Establishing additional sites around the Main Hawaiian Islands

Progress toward these goals is limited by the cost and time required for environmental review, permitting, and construction. At present, the program does not have dedicated funding to pursue expansion.

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Contact

Kim Fuller

O‘ahu District Biologist

Division of Aquatic Resources

Phone: (808) 341‑2770

Email: kimberly.h.fuller@hawaii.gov