A decade-long project to save endangered giant snails from a West Coast coal mine will finish next year.

Just over 6000 Powelliphanta Augustus snails were moved from the summit of Mount Augustus, at Stockton opencast mine, in 2006 and 2007 before Solid Energy began mining there, Hokitika conservation services manager Ian McClure said.

The Department of Conservation (DOC) looked after some of the snails, which can live for up to 20 years, in captivity in Hokitika. Solid Energy took care of predator control and rehabilitation of mined land.

Mr McClure said Solid Energy would not continue funding the project once the 10-year Wildlife Permit expired next year.

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DOC was developing plans for continued management of the endangered snails. Mr McClure said the project had aimed to remedy and reduce the impact on the snails from the loss of their habitat from the opencast mining.

The snails were monitored using a mark-recapture method. Data suggested populations were reasonably secure in the short to medium term as a result of the project, he said.

Of the 6000 snails taken from Mount Augustus, 4000 were translocated, soon after being collected, to two new sites - the Stockton ridgeline and Mount Rochfort.

The remaining 2000 snails and their subsequent offspring have been in captivity as backup for the translocated snails. Some have been released at various stages throughout the last 10 years back into the two rehabilitated areas.

All snails found during the mark-recapture surveys carried out at Stockton over the decade were marked, measured and released. Mr McClure said there was some evidence to suggest the population was growing.

It was unclear if the population growth was a result of breeding, or snails moving in from neighbouring areas.

The snails would take about eight years to reach breeding age.

"The P Augusta populations will need active conservation management beyond 2016 to ensure they are self-sustaining long-term," Mr McClure said.

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Solid Energy could not be reached for comment. The captive snail programme has cost the company around $125,000 a year.

About 800 of the rare snails were frozen to death after a temperature probe failed in a DOC cool room in Hokitika in October 2011.