What is Deep-Sea Hawaiian Black Coral?

Reef Coral vs. Deep-Sea Coral

Hawaiian black coral differs significantly from shallow reef coral. While they share the same name, reef corals are very different in nature and are not used in fine jewelry. Coral is formed deep undersea by microscopic animals called coral polyps—tiny, soft-bodied creatures that form minute, hard shells.

As a colony grows, it takes on complex, branching tree-like forms that allow the maximum number of polyps to extract nutrients from the water. Over time, colonies can form structures ranging from a hand-sized fan to a continent-wide reef.

Precious coral was used in the oldest known form of gem jewelry, with pieces dating back over 25,000 years. Its use even predates the use of pearls, due to its distinctive ability to take a perfect polish.

Hawaiian Black Coral (Antipathes grandis)

Discovery

Maui Divers discovered the first black coral beds found in centuries in deep waters off Lāhainā, Maui, back in 1958. They soon learned that Hawaiian black coral showcased incredible luster and density that would make it suitable for use in fine jewelry. In 1987, Hawaiian black coral was named the official state gem of Hawaiʻi.

Types of Black Coral in Hawaiʻi

In Hawaiʻi, there are fourteen types of black coral, nine of which live at depths of one hundred meters or more. Antipathes dichotoma and Antipathes grandis are the only two species permitted under CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora). Black coral ecosystems in Hawaiʻi are currently managed by the Fishery Management Plan (FMP) for the Precious Coral Fisheries of the Western Pacific Region.

Growth Rates and Locations

Antipathes dichotoma and Antipathes grandis are the dominant and most abundant species, generally found in the channel between Maui and Lānaʻi. Black coral grows into branch-like shapes known as wire or whip corals. Antipathes dichotoma increases in height by about 2.5 inches per year, while Antipathes grandis grows approximately 2.4 inches per year, reaching heights of up to 6.5 feet.

Sustainable Harvesting Practices

Between 2% and 4% of existing coral populations may be gathered annually. Antipathes grandis accounts for only 9% of total black coral harvesting and is harvested exclusively under federal (NOAA) and state (DLNR) regulations. Deep-sea coral's diameter and tree height are measured before harvesting to ensure sustainable practices.

Maui Divers Jewelry and the University of Hawaiʻi pioneered sustainable harvesting of precious coral, leading to regulations and increased awareness worldwide. Most of the global coral industry remains unregulated to this day.

"The fishery is monitored and managed by the Hawaii Department of Land and Natural Resources / Division of Aquatic Resources (DAR), NOAA Fisheries, and the Western Pacific Fishery Management Council, as appropriate. The federal fisheries management regime under the Fishery Ecosystem Plan (FEP) for the Hawaii Archipelago includes mandatory permit and reporting requirements for black coral harvest in the Auau Channel Bed to facilitate monitoring of catch and effort. Regulations allow only selective harvest techniques, such as hand harvest or submersibles, and prohibit harvest of trees with a stem diameter less than 1 inch or a height of less than 48 inches. Black coral harvest at the Auau Channel Bed is also subject to an annual catch limit to prevent overfishing."

"A commercial marine license issued by DAR is required for all commercial fishing activities. It is unlawful to take, destroy, or possess any black coral with a base diameter of less than 0.75 inches from state waters."

Coral Repopulation Research

Ian Chun, a deep-sea coral researcher sponsored by Maui Divers Jewelry, is studying how coral branches can be cut and replanted near existing coral beds to help repopulate coral ecosystems. His research involves bi-annual surveying, planting, and monitoring of these ecosystems. Using fast-setting adhesives, he is testing the hypothesis that coral colonies can be cultivated through cutting and replanting coral trees at depths of 200–250 feet.

The Future of Hawaiian Black Coral

Due to the extreme depths at which precious coral grows, research requires tremendous time and investment. Over the last 60 years, researchers have been steadily advancing sustainability practices and repopulation methods to protect this rare and remarkable gem for generations to come.