Introduction

A problem with a temperature controlled coolroom has resulted in the loss of a number of Powelliphantia snails at its holding facility in Hokitika.

The West Coast Conservancy says a problem with a temperature controlled cool room has resulted in the loss of a number of Powelliphantia snails at its holding facility in Hokitika.

About 800 snails were lost, part of near 6000 originally taken from the Stockton plateau.
 
Approximately 4000 snails have already been relocated to new habitats.
 
About 1600 snails were being held in three temperature controlled cool rooms and environmental chambers as part of the translocation programme and the temperature probe in one container recently failed. DOC says about 800 snails were lost.
 
John Lyall, Technical Support Manager for the West Coast Conservancy says that “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”. “The faulty temperature probe has been repaired and an alert system is being put in place to reduce the chance of reoccurrence”.
 
“Fortunately we’ve already managed to relocate more than 60 percent of the original population into new habitats and we still have more than 800 unaffected snails in the other cool rooms and environmental chambers. 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".

Background

  • DOC has been working with Solid Energy since 2006 on a project to transfer as many snails as possible to new habitats. To date about 4000 of the approximately 6000 originally collected from the Stockton plateau have been transferred. Snails function well in controlled low temperature environments and the remaining snails were kept in the cool rooms as part of the on-going research and translocation programme. The captive population is a backup in case the translocated population fails.
  • Snails 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.
  • DOC organised to have the probe replaced as soon as we noticed the problem. We have also instituted a more regular set of monitoring checks and are currently organising to install an alert system. 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. Some of the snails have been living in these controlled environments for up six years.  The intention is to release all of the snails back to the wild, when this happens is dependent of the success of the current release sites and the rehabilitation of mined habitats. 
  • The captive snail programme has been very successful. Far more snails were recovered from the plateau than we expected and we have put about 4000 of 6000 snails originally found on the plateau back into new habitats.  We are still gathering release monitoring data, and don’t know enough about all the sites, but we do know that at one site the snails have good survival rates. 

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