Researcher and project manager Erina Watene-Rawiri describes her plans to reduce the numbers of koi carp in Lake Waahi. The plan follows the design of the koi carp gates that have been installed and are working successfully at Lake Waikare.
Lake Waahi here, it’s the third largest lake in the Waikato region, and it’s very culturally significant. It’s 522 hectares. Waahi Pa is on the outlet of the lake, and for many generations, it’s relied on this lake for resources – in particular, the eel or the puhi eel, which is the speciality for this region. And essentially, it’s one of the food baskets of the Kīngitanga, so it’s a very significant site, which is why we’ve brought our restoration project here at Lake Waahi.
We’re going to install these one-way koi carp gates so they’ll allow the koi carp to move out of the lakes and into the river, excluding them from the lakes, and then we’re going to fish down the lakes as well, using the locals to come out with specially made koi carp traps, so that’s one way of doing it. The other way is there are these mechanical traps that were developed in Australia – they can catch 2 tonne of coy carp in one lift.
There’s a pilot going out at Lake Waikare at the moment. That works on the natural behaviour of the carp when they’re migrating, they go through these coy carp gates, get caught in the trap and then lift the trap up and kill the carp.
What we want to do is put them into this digester, which turns the coy carp into fertiliser over a period of 3 days. So it goes from the raw koi carp flesh into this granular koi carp fertiliser that we’re going to use in our nursery to grow native plants, which will then get planted back around the lakes.
Our Lake Waahi project co-funded the Lake Waikare project, and our projects going to take the learnings from the pilot that’s happening out at Waikare and apply them here at Lake Waahi, so they’re basically 12–18 months ahead of our project here.
This research is important for the iwi and the community because it’s one step in the pathway back to restoring our lakes and the river. So through the river settlement, there was a fund set up to help restore the Waikato River and the lower lakes. By reducing the koi carp numbers, I think that’s going to be a significant step. There’s no point spending lots of money on riparian margins and planting and all these other projects if the koi carp are just going to come along later, and when it floods, they’re going to get up and eat your plantings and stuff as well. So I think tackling the koi carp first is probably one of the key priorities.
Dr Bruno David, Waikato Regional Council
Beattie & Sanderson (Firm). Beattie & Sanderson, 1897–1900: Prime Minister John Seddon, Māori King Mahuta Tawhiao, and others during a Māori land meeting at Waahi Pa, Waikato. Ref: PA7-01-39. Alexander Turnbull Library, Wellington, New Zealand. http://natlib.govt.nz/records/23181243
Sir George Grey Special Collections, Auckland Libraries, AWNS-19061213-9-1.
Beattie & Sanderson (Firm). Beattie & Sanderson: Group portrait of Premier’s visit to Huntly, escorting King Mahuta back to Waahi. Ref: PA7-01-38. Alexander Turnbull Library, Wellington, New Zealand. http://natlib.govt.nz/records/22876411
The Waikato Tainui College for Research and Development acknowledges the financial support given by the Waikato River Cleanup Trust Fund which is administered by the Waikato River Authority.
The Waikato River Cleanup Trust does not necessarily endorse or support the content of the publication in any way.