Learn about Hawaiian Black Coral - Hawai'i's State Gem

Divers diving for black coral

Reef Coral vs. Deep Sea Coral

Hawaiian black coral differs from shallow reef coral (Grigg). While they share the same name, "coral," reef corals are very different in nature and are not used in fine jewelry. Corals are formed deep undersea by microscopic animals called coral polyps. These tiny, soft-bodied creatures form minute, hard shells.

As a colony grows, it takes on complex branching, tree-like forms, which allows the maximum number of polyps to extract nutrients in 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 form of gemstone jewelry, with pieces dating back over 25,000 years. The use of coral, whose distinctive feature is that it can take a perfect polish, even predates the use of pearls.

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 jewelry. In 1987, Hawaiian black coral would even be named the state gem of Hawaiʻi.

Types of Black Coral Coral:

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

Growth Rates and Locations:

Antipathes dichotoma and Antipathes grandis are the dominant and most abundant species. Generally found in the channel between Maui and Lanai, 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 grow 2.4 inches per year, reaching heights of up to 6.5 feet.

Sustainable Harvesting Practices:

Between 2% and 4% of existing coral populations can be gathered annually. Antipathes grandis only accounts for 9% of total black coral harvesting and is only harvested under federal (NOAA) and state (DNLR) regulations. Deep-sea coral's size (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 at the beginning, leading to regulations and awareness worldwide. Most of the coral industry worldwide is still unregulated.

Currently, "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 and implementing regulations under 50 CFR 665.260 through 665.270 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. This fishery corresponds to the following fishing method(s) defined by DAR: black coral dive. It is unlawful to take, destroy, or possess any black coral with a base diameter of less than 0.75 inches from state waters" (Fisheries, NOAA).

Repopulation:

Ian Chun, a deep-sea coral researcher, sponsored by Maui Divers Jewelry, examines how coral branches can be cut and replanted in the vicinity of coral beds to help repopulate coral ecosystems. His research involves bi-annually surveying, planting, and monitoring these ecosystems (Ian Chun, personal communication, October 7, 2021). Using fast-setting adhesives that were previously nonexistent, he plans to test his hypothesis that coral colonies can be grown using the practice of cutting and replanting coral trees at depths of 200-250 feet.

Future:

Due to the depths at which precious coral grows, research requires tremendous time and investment. Over the last 60 years, researchers have been working towards bettering sustainability practices and repopulation.

Sources:

Bruckner, Andrew, et al. "CASE STUDY FOR BLACK CORAL FROM HAWAII." CITES, 2008.

Fisheries, NOAA. “Hawaii Black Coral Diving Fishery - Mmpa List of Fisheries.” NOAA, 11 July 2022.

Grigg, Richard. "Hawaii's Precious Corals." Island Heritage. Norfolk Island, Australia, 1997.