Lamprey have a large 'sucker' full of teeth. Photo: Supplied / DOC
Five previously unknown locations used by an elusive and threatened taonga species have been identified in Otago.
Lamprey or kanakana are a jawless, migratory fish that look like an eel and are born upriver, travel to the ocean as adults before returning to rivers to spawn.
The Department of Conservation and Te Nukuroa o Matamata have deployed pheromone detectors into the Taieri catchment to find them after using environmental DNA to suggest possible spawning streams.
Kanakana only migrate at certain times of the year, with adults moving mostly at night and hiding during the day, their nests usually buried underground, and as larvae they bury themselves in sediment.
DOC's Freshwater Technical Advisor Dr Christopher Kavazos said adult kanakana used large sensory organs to detect pheromones the larvae give off to guide them to certain waterways with good habitat.
"These are big waterways, these are small larvae so they're excreting small amounts of pheromone, and as Dr Cindy Baker has stated before, these samplers that she's developed, they can pick up about a teaspoon of this pheromone in the equivalent of 580,000 (Olympic) swimming pools. So they're super sensitive."
It was a huge win to find more evidence of lamprey, he said.
"They're a taonga species, a source of mahinga kai for Māori, and they're real survivors, with traits reminiscent of our earlier ancestors.
"Lamprey split off from our evolutionary chain more than 360 million years ago so, unlike virtually every other species of vertebrates, they didn't evolve a jaw."
An adult lamprey. Photo: RNZ / Alison Ballance
The sampling showed that lamprey in different tributaries in the lower half of the Taieri catchment, but they weren't going as far as initially expected, he said.
Locating waterways they relied on meant they could put extra care into protecting them as they faced pressures from loss of habitat, pollution and extreme weather, Kavazos said.
"They used to be plentiful across the country, and there are stories of massive harvests in the past. Now they are classified as Threatened-Nationally Vulnerable."
He wanted to develop an annual monitoring programme in the Taieri catchment.
"If we start witnessing declines or something, then at least we're starting to monitor.
"At the moment, we virtually do no monitoring for lamprey in New Zealand so this is starting to build on that picture so we can start to really understand the status of these fish."
Te Nukuroa o Matamata is excited its rangatahi are helping to protect the threatened native fish.
The project is part of Jobs for Nature and was set up by Otago Peninsula based Te Rūnaka ō Ōtakou, a hapū of Ngai Tahu.
Paul Pope manages the team and said they are mainly young people learning about freshwater and conservation science.
"It's really exciting for them, especially for young hapū members, to actually realise the possibilities and the future of kanakana coming back into the mahika kai basket of the hapū".
Pope said through colonisation and loss of habitat Ngai Tahu people lost connection to the Tairei river.
"This project is about is reconnecting some of those people to the wetlands and waterways, and managing those areas. Also, associating some of the skills and knowledge from the past but also skills and knowledge of the future as well".
Pope said Te Nukuroa o Matamata is supposed to come to an end in the middle of next year.
But he said Ōtakou is determined to keep it going.