Whiskered introduced species, catfish, have taken over and they’re killing New Zealand’s native fish species.
Wiremu Anaru and his team from Te Arawa Lake Trusts are on the case – they’re known as the Catfish Killas. Since 2016 the group has hauled up about 150,000 catfish from Rotorua and Rotoiti.
Catfish were introduced in the 1870s and they’re a problem because they prey on koura or freshwater crayfish, as well as other native fish that are considered threatened.
“Catfish eat all the babies – they just go along the bottom of the lakes and suck them all in,” William Anaru told The Hui, while out setting nets on Lake Rotoiti.
The explosion of catfish numbers started when a single fish hitched a ride from the central North Island – a biodiversity mess that could have been avoided had the boat been cleaned.
“They say it came from a boat that had been in Lake Taupo for about three days and a little catfish swam up into the boat trailer and got a ride from Taupo to Rotoiti,” Anaru said.
And with that, the cat was literally out of the bag.
Catfish release 6000 eggs each spawning cycle, so one fish quickly becomes a multitude. That’s when the iwi, Te Arawa, stepped in.
So big is the task of getting rid of the slimy pests that hundreds of rangatahi (young people) from across the rohe (area) are lending a hand.
“The catfish can survive out of water for like two days, because they can survive in their own slime,” one of the student volunteers, Mikaere, told The Hui while holding a large catfish on the lakefront at Rotoiti.
When Anaru’s koro was a boy Rotorua and Rotoiti were teeming with koura. Numbers are now down 80-90 percent.
“When you fed your manuhiri (visitors) you’d feed them koura. It was like a display of mana, how much koura you could provide to visitors,” Anaru said.
“The practise of harvesting koura, it’s something our tipuna used to do. It’s something by right we should be able to continue to do forever.”
Populations of kooaro, a fish species, have also been decimated. For Anaru it’s not just the loss of the species at stake, but connection to his tipuna through stories.
“The actual name of Lake Rotoiti is Te Roto-Whaiti-i-kite-ai-a-Ihenga. It means a small lake discovered by Ihenga.
“So Ihenga was an explorer from Te Arawa that came up from Maketu, came up the Kaituna river, and he had two dogs with him on his journey. His dog ran off in front of him and then they came back and they spewed up a whole bunch of kooaro at his feet.
“So he knew that there was a waterway area and that he could get a kai.”
Anaru and his team of young conservationists are being credited with removing about 30,000 Catfish from Rotorua waterways each year. It’s a source of pride for Te Arawa rangatahi.