Harvesting Impacts and Invasion by an Alien Species Decrease Estimates of Black Coral Yield off Maui, Hawai'i

Abstract

For over 40 yr, the black coral fishery in Hawai'i has been managed successfully. However, three new developments now threaten sustainability of the resource. First, harvesting pressure on increasingly smaller colonies of both species of commercial black coral (Antipathes dichotoma Pallas and Antipathes grandis Verrill) has increased. Since 1976, the biomass of black coral in the overall bed off Maui, Hawai'i, has decreased by about 25%. Second, at depths between 80 and 110 m off Maui an alien species, Carijoa riisei (Duchassaing & Michelotti), has overgrown large areas of the substratum as well as many adult colonies of both species of commercial black coral. This invasion may be contributing to a decrease in the recruitment of both species of black coral at shallower depths. Third, increasing sales of black coral jewelry in recent years is also placing more demand on the resource. Taken together, these trends suggest a need for more stringent regulations, including a larger size (height) limit, a reduction in the maximum sustained yield, and possible reassessment of the economics of the fishery. Adoption of these or other measures would help to extend and ensure continued sustainability of the black coral fishery in Hawai'i and long-term conservation of the resource.