Source: Department of Conservation
Written by Environment Canterbury.
About 200 trout have been relocated within Hororata’s Bealey Stream as part of a wider project to protect the ‘Nationally Critical’ Canterbury Mudfish/kōwaro.
The Brown Trout were situated upstream of an underwater electric barrier, which is providing a safe haven for kōwaro in a pocket of habitat on Haldon Pastures Farm.
The solar-powered ‘fish fence’ was activated in 2021 and is thought to be the first of its type in the Southern Hemisphere. It consists of three underwater iron structures, which send out electric pulses to discourage trout from moving upstream – where they would otherwise predate on the mudfish. This has increased the upstream habitat size for this taonga species from about 800 metres, to 8,000 metres.
The project is a joint effort between Department of Conservation (DOC), Environment Canterbury, Fish and Game New Zealand, Fonterra and landowner John Grigg.
The agencies recently pitched in to relocate the residual trout population to the downstream side of the fence, to keep them away from the kōwaro.
An electric fishing method was used to capture the fish, which were then put into buckets, measured, and safely relocated. More than 70 trout were caught and transferred over a five-day period in early March, and since then, about 130 more have been moved.
Environment Canterbury Pou Matai Ko (Cultural Land Management Advisor), Steve Carrick, said this year’s low water levels were advantageous for electric fishing, as it improves access.
“This is the second year that we’ve got together for a week and come out and blitzed it. But this time, we were able to get to areas that we wouldn’t usually be able to.”
He said the joint agency approach is key to the success of not just the trout transfer exercise, but the overall barrier project.
“It’s great to have those other agencies working with us, because their skillsets and knowledge bases, particularly from the DOC team – for the history of this place, gives us that long-term view.
“Of course, none of this work would be possible without the landowner’s cooperation. John’s willingness to give us access to the property and his support of these preservation initiatives, is invaluable.”
John is praising the ‘outside the box’ approach to protecting the kōwaro.
“It’s great to be involved in something so innovative, and totally different. Often you do have to think outside the square to protect nature.”
DOC biodiversity supervisor, Craig Alexander, said mudfish numbers have been declining over the years, and the barrier is one way of trying to secure populations into the future.
“The next round of population monitoring is due to be carried out in winter, so it will be interesting to see whether there’s any evidence yet of the barrier’s success.”
The joint team is also working with the barrier’s North American manufacture, Smith Root, to explore other ways of proving its functionality, without stressing the fish samples.
Video: Environment Canterbury
