The state Department of Land and Natural Resources is seeking approval to hold public hearings on new regulations that would protect certain species of limu-grazing fish in waters off North Ka'anapali, where an invasive seaweed is endangering the reef ecosystem.

The new administrative rule would create the Kahekili Herbivore Fisheries Management Area, whose boundaries stretch from Keka'a Point, more commonly known as Black Rock, north to Honokowai Point.

The Hawai'i Coral Reef Initiative identified Kahekili Beach as one of its top areas of ecological concern in 2008 because it is inundated with Acanthophora spicifera, a red alga with spiny branches. Like other alien algae, it competes for space on the reef, displacing native species and smothering live coral.

High levels of nutrients from runoff along developed coastlines and smaller numbers of plant-eating fish are believed to be factors fueling the growth of invasive algae.

Sea urchins, parrotfish, manini and other fish eat the seaweed and would be protected within the management area as part of a project to test their effectiveness as a natural control. The Hawai'i Coral Reef initiative is funding the research, which involves the DLNR's Division of Aquatic Resources, the University of Hawai'i and other groups.

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.

Feeding fish within the area also is prohibited.

The rule additionally allows for permits to fish in the management area.

The Board of Land and Natural Resources is scheduled to consider the Division of Aquatic Resources' request to conduct public hearings on the rule at its meeting Friday.

A. spicifera is the most widespread alien alga in Hawai'i. It is believed to have been introduced to the Islands in the 1950s by a barge from Guam.

The spiny seaweed 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.