Black Coral: History of a Sustainable Fishery in Hawai'i

Abstract

The black coral fishery in Hawai'i has been sustainable for the past 40 yr. The fishery began in 1958, shortly after its discovery off Lahaina, Maui, by Jack Ackerman and Larry Windley, who later formed the company Maui Divers of Hawaii. Since that time, the black coral jewelry industry has gradually expanded and is valued in Hawai'i today at about $15 million at the retail level. In the 1970s, studies of the population dynamics of the major species established growth, recruitment, and mortality rates and led to the development of management guidelines including recommendations for a minimum size and maximum sustained yield. Results of a recent survey in 1998, reported in this paper, show that rates of recruitment and growth are near steady state and appear to account for the long-term stability of the fishery. However, recent technological advances and potential increases in demand could lead to increased rates of harvest. Should this happen, more stringent regulations may be required to avoid overexploitation of the resource.

This paper outlines the history of the black coral fishery in Hawai'i and reports the results of a recent survey of the Maui black coral bed conducted in 1998. The objectives of the survey were to obtain measures of abundance, recruitment, and size frequency of the two main species, Antipathes dichotoma Pallas and A. grandis Verrill, and to evaluate the sustainability of the resource. In brief, the goal was to reassess maximum sustainable yield of black coral in the 'Au'au Channel bed off Maui.

History of the Black Coral Fishery in Hawai'i

The black coral fishery in the Hawaiian Islands began in 1958 when a large bed of black coral consisting primarily of A. dichotoma and A. grandis was discovered off Lahaina, Maui, by Jack Ackerman and Larry Windley (Grigg 1965). The site of their original discovery was 4.8 km west of Lahaina in the middle of the 'Au'au Channel between Maui and Lāna'i at depths of 30-90 m (Figure 1).

Subsequent exploration by these pioneers showed that the 'Au'au Channel bed extended for many linear kilometers along steep topographic drop-offs in the channel between Maui and Lāna'i. Recognizing the value and extent of their find, Ackerman and Windley started a small business in Lahaina, Maui, in 1958, for the production and sale of black coral jewelry. They named their small company Maui Divers of Hawaii (Stewart 1962).

The harvest of black coral in Hawai'i has traditionally been carried out by scuba divers. In the early years of the fishery, divers harvested black coral by cutting or breaking the coral from the bottom with an ax and sledge. They then tied the coral to their boat anchor lines (Figure 2). At the end of the dive, the anchor and coral "trees" were buoyed to the surface by inflating lift bags on the bottom. Lift bags are still used today to float the coral to the surface, but the divers no longer anchor over the beds. Instead, they use a "free boat" method in which the boat follows lift bags as they reach the surface. The divers ascend with their last lift bag (Figure 3) and decompress while the boat drifts above them on the surface. On an average dive, two to four trees (colonies) of black coral are harvested; each colony weighs between 2 and 5 kg (5-10 pounds). The total weight of coral harvested per dive, per diver, averages ~10 kg (22 pounds) and is valued in today's market at $25/pound. The depth range of harvested black coral is 40-75 m (130-250 feet).

Figure 1.

Map showing the location of black coral beds in Hawai'i.

Between 1960 and 1970, the black coral jewelry industry in Hawai'i grew steadily. By 1969, about one dozen small companies had joined Maui Divers and together they produced about $2 million in gross sales of black coral jewelry. Although the economic potential of the industry had been firmly established by...