COURTESY U.S. FISH AND WILDLIFE SERVICE
Newcomb's snail is found only on Kauai and has an estimated population of 6,000 to 7,000.
Plan moves rare Kauai snail
Federal officials want to expand the habitat of Newcomb's snail
WAILUKU » A species of snail native only to Kauai will be moved to other stream and river locations on the island, under a federal recovery plan.
Newcomb's snail populations once lived in the Hanakoa Stream, Hankapiai Stream and the Wainiha River, but are no longer found there.
In a recovery plan published in the Federal Register yesterday, U.S. Fish and Wildlife officials said they will be assessing whether to return the snails to the old stream locations, as well as settling them in other habitats.
The recovery plan follows a draft plan released for public comment in March 2004.
The snail, known by its scientific name Erinna newcombi, is located in about six streams and rivers on Kauai with an estimated population of between 6,000 and 7,000, and about 90 percent of the population distributed mainly in two of the streams.
Federal officials said the species is highly susceptible to extinction given its small numbers and limited habitat area.
The snail has a nearly smooth, brown to black shell formed by an oval whorl that is about a quarter of an inch long and a little wider than a tenth of an inch.
Federal officials said they don't have historical information on the population of the snails at the streams, including Kalalau Stream, Lumahai River, Hanalei River, Kealia Stream, Makaleha Stream and the North Fork Wailua River.
But officials said anecdotal reports indicated there are more snails at Kalalau Stream and Lumahai River.
Besides researching what makes the snails thrive or die in an environment, a key element in recovery is the maintenance and protection of adequate water flows at the stream and spring sites containing them, officials said.
Federal wildlife officials said they intend to maintain adequate stream flows through coordination and cooperation with state departments and agencies, including the state Commission on Water Resource Management and the state Department of Land and Natural Resources.
Officials said Newcomb's snails face a continued threat from human-caused changes to the water conditions on Kauai.
They noted that the first collection and description of the species by western naturalists occurred in 1840 and that Newcomb's snails were collected at a place called Hanapepe Falls.
The recovery plan said a large irrigation diversion structure is now built into the base of the falls and the stream has areas that are entirely dry much of the time.
The specific effects of surface-water diversion or groundwater withdrawal on the Newcomb's snail are unknown, but none of the known snail populations are found below points of significant water diversion, the plan said.