Saturday, March 2, 2024

Commercial venture to eradicate koi carp under way

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North Waikato iwi are establishing a commercial fishing venture on Lake Waikare in an attempt to halt the koi carp plague and improve the lake’s water quality.
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Reducing koi carp numbers down to a manageable level will not only improve Lake Waikare’s water quality, but provide employment and commercial opportunities for local iwi, Te Rui o Waikato chairman Tawera Nikau says.

North Waikato iwi are establishing a commercial fishing venture on Lake Waikare in an attempt to halt the koi carp plague and improve the lake’s water quality.

The lake, northeast of Huntly, has a well-documented history in recent years of environmental degradation because of koi carp infestation and nutrient loading from farms and treated wastewater from Te Kauwhata.

The lake’s shallowness and high sediment levels make restoring the lake difficult, according to the Waikato Regional Council (WRC). In recent years, the lake’s water has turned an ugly shade of orange because of algal growth.

The lake sits on the doorstep of Tawera Nikau’s farm and marae. Once, the lake had an abundance of native fish species and wildlife and turning around the lake’s water quality to allow those species to thrive will be intergenerational, he said.

“The koi carp [eradication] is one of the things we can do as mana whenua to make sure we are doing something because nothing’s been done.”

Nikau chairs Te Rui o Waikato (TROW) a collective of 15 Waikato Tainui marae that aim to deliver economic and social outcomes for its members. This collective is spearheading the venture to restore the lake with the support of the WRC and DOC.

It will see the creation of a fishing fleet to catch and convert the carp into fertiliser, petfood, burley or fish bait, with the money generated from these products re-invested back to further expand the fish harvest.

Its goal is to get koi carp back to a manageable level, Nikau said.

“What we want to do is utilise that koi carp fish and re-invest that money back into purchasing more boats, more people out there trying to be upskilled.

“We want all of our river and lake maraes to be able to train the young people up to be able to do the environmental work.”

TROW have also applied for further funding from the Government to increase the scale of the fishing operation, which in turn will provide greater employment opportunities, he said.

This will enable them to employ another nine people and add three more boats and vehicles to their fleet. He understood the funding had been allocated but had been delayed because of covid-19.

These new employees could also be upskilled by getting them to qualify as boat skippers and improve their fishing skills. He estimates it could employ as many as 20 people.

The venture was operating over the past 12 months but is now on hold until that funding is received to allow them to ramp it up.

“On a daily basis, we were taking about 1.5 tonnes out of the lake – that’s with one boat,” he said.

The boats are worked by three people, who cast out nets and then collect the nets the following day.

Once caught, the carp are then processed either for fertiliser or fishbait. Once the fillets are removed for bait or burley, the remaining frames and guts are turned into a mince-like slurry that can be spread onto crops.

Nikau trialled the fertiliser on his maize crop last year and said it was the best crop he has ever grown. Using the fertiliser resulted in a 30% reduction in his use of commercial fertiliser.

He was also working with the ESR and the University of Waikato to study the impact the fertiliser has on nitrogen leaching levels.

Areas around the lake’s boundary have also been planted up in natives to further reduce nutrients entering the lake.

A separate study is also being undertaken in partnership with the council to better understand koi carp numbers in the lake. This will help better understand what a sustainable number of carp in the lake looks like, he said.

Other farmers in the catchment also back the venture and are committed to doing their part in reducing the nutrient loading entering the lake.

He says it’s been a long road for TROW to finally come up with a solution to the lake’s carp infestation, particularly around working through compliance issues around getting a commercial licence for farming a pest species.

Now that it’s a reality, Nikau said they are focusing on getting it fully up and running and then eventually, expanding the operation to nearby lakes that are also infested with koi carp.

“There’s some smaller lakes that we know we could fish out in a matter of months.”

But for now, he says, the focus is fully on Lake Waikare.

“As mana whenua we can instigate our kaitiakitanga on the lake. Let’s start with this lake and then go to all of the lakes and utilise the experience and knowledge to get down to manage the koi carp species.”

He hopes that the efforts will be rewarded over the next 25 years.

“This is a start and you have to start from somewhere. Hopefully in my grandkid’s time, they will be able to utilise the lake.”

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