A problem with a Department of Conservation temperature controlled coolroom has lead to about 800 rare snails freezing to death.
The Powelliphantia snails, which were held at a holding facility in Hokitika, can withstand freezing temperatures in the wild for short periods but a temperature probe in one of the three cool rooms failed, exposing the snails to a prolonged period of low temperatures.
"The snail deaths are very upsetting as staff are committed to the care of the snails, and previous to the loss had been proud to be celebrating a great captive breeding result," John Lyall, Technical Support Manager for the West Coast Conservancy says.
"The faulty temperature probe has been repaired and an alert system is being put in place to reduce the chance of reoccurrence."
Nature conservation organisation Forest & Bird said it is devastated that snails have died in a Department of Conservation fridge.
First, their natural home was destroyed for a coal mine on Stockton Plateau, and now theyve died in captivity. This tragedy was entirely avoidable, Forest & Bird Conservation Advocate Nicola Vallance said.
This is a sharp lesson that moving native animals from their natural habitat doesnt work.
The snails were part of some 6000 originally taken from the Stockton plateau.
Around 4000 snails have already been relocated to new habitats.
"The remaining snails are breeding well, producing good numbers of eggs, and we expect the captive population to recover the loss within a few years," Lyall said.
DOC says more regular monitoring checks would be carried out in the future but there is no guarantee other probes wont fail.
The cost of the captive programme is about $125,000 a year, which is paid by Solid Energy.