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RNZ News
a day ago
- General
- RNZ News
DOC spends hundreds of thousands to care for snails after mining destroys home
Powelliphanta augusta snails and eggs. Photo: Lisa Flanagan/DOC Two thousand giant snails are living in fridges on the West Coast as an insurance policy for the Department of Conservation, which has spent hundreds of thousands of dollars on their care and restoring their environment-turned-coal mine. The Department of Conservation (DOC) has managed this captive population of Powelliphanta augusta since 2006, when the former state mining company Solid Energy took over their habitat on the Mt Augustus ridgeline on the western side of the Stockton Plateau, near Westport. Solid Energy collapsed in 2015 , after falling coal prices left it unable to pay almost $400 million of debt. Bathurst Resources now owns the mine, and the captive population of snails in DOC's care is now just under 2000, kept in containers with leaf matter in a temperature-controlled room in Hokitika. An Official Information Act request submitted by the Taxpayers' Union shows DOC has spent more than $411,000 in the past four years on their housing and management, including staff costs. But the Taxpayers' Union's investigations coordinator Rhys Hurley said this was a poor use of public money, and the scheme "shows the ridiculousness of the system". "It drains DOC funding away from other species, is unaccountable and offers little evidence of success," he said. The Department of Conservation (DOC) has managed this captive population of Powelliphanta augusta since 2006. Photo: Lucy Holyoake/DOC But DOC's principal advisor for biodiversity Hilary Aikman said those costs were "really reasonable", and on-par with what the department would spend on any other critically endangered species. She had just returned from a "very wet but fascinating trip" to Stockton this past week. "The idea is that [the captive snails] provide us with an insurance population while we understand how they've adapted to the areas where they were released that were away from their original habitat," Aikman said. The snails' original habitat had measured only 10 hectares, almost all of which had been converted into the mine. The bits no longer in use were now being revegetated, with plants being brought in from nearby areas to try and recreate a habitat for these snails to be released into. Some snails had survived in the wild and lived on around the mine, but up to 10,000 snails and eggs had been reintroduced to those areas from the captive population. It was a slow process, Aikman said, as the species was slow to mature - some in captivity had reached up to 30-years-old. "We are being somewhat cautious, making sure that they're surviving before we let more out of captivity, but that is because they're critically endangered, they're as rare as the kākāpō, and they're unique to New Zealand." Aikman said one of the benefits to having a captive population was the opportunity to learn more about the species. Most of the revegetation work was being undertaken by Bathurst, who now ran the mine. Photo: Lucy Holyoake/DOC Last month, DOC ranger Lisa Flanagan, who had been looking after the snails in Hokitika for more than 12 years, filmed an egg being laid - something that never would have captured in the wild. Not all of the cost of the species' survival had been shouldered by DOC. "The majority of the money to keep the captive population going came as part of the permitting permissions for Solid Energy when they were first set up," Aikman said. "That was part of the agreement - if you remove the habitat, this is what we need to do." And most of the revegetation work was being undertaken by Bathurst, which now ran the mine. "We feel that the costs we are spending on them, and we've spent a little bit more recently on supplementing some of the planting to help with the restoration, but we feel that those costs are really reasonable for a critically endangered species, and are quite in-line with what we spend on other critically endangered species." She said they had begun to limit the breeding of snails for which they already had plenty of genetic material, but allowing others with rarer traits to continue, to increase the diversity of the population. According to the OIA, in 2023/24, $85,000 had been spent on a population genetics study to reveal the existing level of diversity. Aikman said the goal was to release most, if not all of the snails over the next five years. Sign up for Ngā Pitopito Kōrero , a daily newsletter curated by our editors and delivered straight to your inbox every weekday.
RNZ News
07-05-2025
- Science
- RNZ News
Rare snail saved from mining captured laying egg on camera
A rare and threatened species of West Coast snail has been captured on camera laying an egg for the first time. The Powelliphanta augusta snail was being weighed by Department of Conservation (DOC) ranger Lisa Flanagan in when the little egg emerged from its neck. DOC had been managing a captive population of the snails in chilled containers since 2006, when Solid Energy started mining their habitat on the Mt Augustus ridgeline on the western side of the Stockton Plateau near Westport. Flanagan said it was a special moment after 12 years looking after the snails. "It's remarkable that in all the time we've spent caring for the snails, this is the first time we've seen one lay an egg. "We caught the action when we were weighing the snail. We turned it over to be weighed and saw the egg just starting to emerge from the snail," she said. Very little was known about the snails when they were taken into captivity and staff were constantly making new discoveries, she said. "I just love watching their progress each month, weighing them, how their shells develop and all the interesting things they do," she said. "Powelliphanta augusta are slow growing and long lived, not being sexually mature until they are about eight years old and then laying only around five big eggs annually which can take more than a year to hatch. "Some of our captive snails are between 25 and 30 years old - in this they're polar opposites to the pest garden snail we introduced to New Zealand which is like a weed, with thousands of offspring each year and a short life." A rare and threatened species of West Coast snail has been captured on camera. Photo: Supplied/Department of Conservation DOC senior science advisor Kath Walker said the hard shell that helped the snails retreat also posed some problems with mating and egg-laying. "Powelliphanta have solved this by having an opening (a genital pore) on the right side of their body just below their head so that the snail only needs to peek out of its shell to do the business," she said. "It extends its penis out of this pore and into its mate's pore, and its mate does the same, simultaneously exchanging sperm, which they can store until they each fertilise the sperm they've received to create eggs. "As hermaphrodites, they have both male and female genitalia, so although they usually mate with another to cross fertilise their eggs, as carnivores which have to live at relatively low density, being able to occasionally self-fertilise must help with survival of the species." Before their habitat was mined, about 4,000 snails were collected and moved to nearby sites. A further 2,000 snails were used to start a captive colony. The snails were mostly housed individually in containers, on moss and litter, and fed worms appropriate to their size once a month. They were regularly measured and weighed. In March there were 1,884 snails from hatchlings through to adults and 2,195 eggs in captivity. DOC had established new populations of the snail in the wild and reintroduced them to new and rehabilitated habitats. A captive population would be managed until DOC was confident the species would survive in the wild. Sign up for Ngā Pitopito Kōrero , a daily newsletter curated by our editors and delivered straight to your inbox every weekday.
