LAHAINA — The Department of Land and Natural Resources will hold a public hearing tomorrow on a proposed rule that would establish the nearshore waters of north Ka'anapali as a herbivore fisheries management area.

The proposed rule is intended to maintain the population of limu-eating fish and sea urchins to help control the overgrowth of algae on coral reefs in the areas between Keka'a Point, also known as Black Rock, and Honokowai Park.

Information on the proposal will be presented from 5:30 to 6 p.m. at the Lahaina Civic Center, followed by the public hearing from 6 to 8 p.m.

The proposed rule would create the Kahekili Herbivore Fisheries Management Area. The rule bans injuring, killing or removing members of the acanthuridae family of fish, which includes surgeonfish and tangs such as 'api, kala, kole, manini and palani. Also protected are sea chubs, rudderfish, nenue and other members of the kyphosidae family; parrotfish, known as uhu, and other members of the scaridae family; and sea urchins.

The invasive seaweed Acanthophora spicifera, a red alga with spiny branches, is endangering the reef ecosystem in the area proposed for protection. Like other alien algae, it competes for space on the reef, displacing native species and smothering live coral.

A. spicifera is the most widespread alien alga in Hawai'i, and usually attaches to rocks or dead coral heads. Because it is brittle and its branches are easily broken into fragments, it can spread rapidly and is found floating freely in large masses.

Much of the once-healthy reefs off west and south Maui have become largely dominated by algae, according to the DLNR. The Hawai'i Coral Reef Initiative identified Kahekili Beach as one of its top areas of ecological concern because of the algae inundation.

Invasive algae also threaten Kane'ohe Bay, Waikiki and Maunalua Bay on O'ahu.

Maintaining healthy populations of herbivorous fishes on the coral reefs is critical to maintaining a reef's biological diversity, DLNR said.