One hundred Waikato eels now have a safe new home in Lower Nihotupu Dam.
The eels were part of a fisheries quota and would have been sold as food, but water quality scientist Matthew Hubrick expects them to now live a long and happy life feasting on pest fish like perch and rudd, and by doing so, they'll be improving the water quality in the dam.
"Perch and rudd are terrible for water quality because they eat the zooplankton and other creatures that do us a favour by eating the algae.
"These eels are big enough to eat the pest fish, and since there's no fishing in our water supply lakes, they're now in a really safe environment."
Matt came up with the idea of using adult eels to help keep the perch and rudd populations under control. With Ministry of Primary Industries' permission, and after consultation with iwi in Auckland and Waikato, he bought 100 NZ longfin eels and arranged their transportation to Lower Nihotupu Dam.
"This is the first time we've used eels to try to control the pest fish. The NZ longfin eel are the most endangered eel species in New Zealand, they're native and they're the most voracious predator – they're perfect for the job," Matt says.
The eels were transported in polystyrene chilly bins to keep them cool and calm for the journey from Te Kauwhata this morning.
Seven Sharp reporter Lucas De Jong and cameraman Leigh Fraser were there to record the action, so tune in to Seven Sharp tonight to see their story.
For Matt, a self-professed 'fish nerd', to see the eels wriggle off into the depths of the lake was especially rewarding.
"I love fish – I've got three aquariums myself and I breed fish at home. For me to release 100 amazing and endangered animals like this, it's a great sense of achievement.
"I think if I had a spirit animal, it would be the NZ longfin eel – they're amazing animals and are revered in many cultures as a symbol of strength."
Today's eel release is a trial. Matt hopes to see a revival of zooplankton and reduction in perch and rudd, which will prove the plan is working.
"Next time, I'm hoping we'll be putting 1000 eels into the reservoir."
Head of operations excellence Priyan Perera admits being dubious when he first heard the proposal, but soon came around.
"I think the potential is huge. I don't think anyone else has even looked at anything like this to control pest fish in the country. It's an awesome idea."