School children, lakeside residents, marae groups, and eco-warriors are leading the fight against the dreaded bullhead catfish but have hit a cruel snag after nets were stolen. Some were bought after the hardy North American species spread from Lake Rotoiti to Lake Rotorua in December. It was first found in Te Weta Bay in 2016, and in the 2017/2018 summer, the population boomed. Catfish are a threat to native fish, kōura and their eggs. They also compete with some trout and eat their eggs. The bottom feeders can also deteriorate water quality by bringing up sediment.
Ten catfish "fyke" nets, each worth $300, have been stolen from Lakes Rotoiti and Rotorua, since the start of the year.
The latest two were taken last week.
One was being monitored by a Bay of Plenty Regional Council contractor, and the other had been enthusiastically taken on by Kaitao Intermediate pupils.
Others at Lake Rotoiti have been emptied, returning catfish into the lake.
A net at Lake Okareka, checking that catfish have not spread there, has also been recently slashed.
Volunteer co-ordinator William Anaru told the Rotorua Daily Post it was not just a financial insult, but it left volunteers heartbroken and in limbo because replacement nets take months to arrive from their specialist manufacturer overseas.
"They take forever to get here ... Nets only just arrived this month to replace the five that were stolen before the end of February."
He said the pupils, like all volunteers, had been working hard to service the nets each day and restore the mauri of the lakes.
"Now that has been put on hold because of thieves."
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To date, 65,000 catfish have been caught in Lake Rotoiti, and 200-300 in Lake Rotorua, under the programme being lewd by the Te Arawa Lakes Trust and the Bay of Plenty Regional Council.
Kaitao Intermediate pupil Alyssa Mansner said she had been looking for catfish each Thursday, and protecting trout eggs, as part of the school's Tāngata Taiao project.
She said the net theft was disappointing.
"Now we can't find as many fish."
Mansner said she loved having the privilege to catch them.
"I now know a few more fish names. Some of the fish names are Cockabullies, smelts, catfish and mosquito fish."
Fellow pupil Laval Wilson said: "On the first day of our study we got a handful of cockabullies and a mosquito fish. Then, not too long ago we got a catfish."
"We use an app to track how many different species of fish we catch. We also track the temperature of the lake each time we go."
Anaru asked residents to ask around about the stolen nets.
He said there would be no repercussions if they were given back voluntarily to the Te Arawa Lakes Trust office on Haupapa St.
So far, one person has been caught stealing a net and was ordered by a witness to return it.
Some volunteers come from as far afield as Auckland and Wellington to help, and others based in Rotorua travel up to 20 minutes each way to reset their nets.
Each net has a notice showing they're part of the culling project.
How to stop the spread
Before you leave a lake, waterway or river, make sure you remove all weeds from your boat trailer and gear and check for catfish
Empty any lake water or ballast you may be carrying
Don't leave your trailer in the water
If you want to help in the netting programme, email William Anaru at firstname.lastname@example.org or go to the Te Arawa Catfish Killas Facebook page
What are catfish?
• Nobody really knows why catfish were introduced into New Zealand but they came here in the 1870s. They are now widespread in the Waikato River system and North Island lakes, including Taupō
• Catfish can live in a wide range of temperatures and low-quality water
• They can survive for long periods out of water, about 48 hours
• The Department of Conservation wants anyone catching catfish to kill them, and not return them to the waterway