Bay of Plenty locals fight back against pesky catfish invading waterways

Invasive catfish have hit record numbers in Bay of Plenty waterways, but locals are fighting back.

Over the past two years, a group known as the Catfish Killas has waged war on the pesky invaders, inflicting some serious damage.

They've been dubbed the possums of the water but apart from the whiskers, there's not much resemblance - except that the slippery pests are also damaging New Zealand wildlife.

"They can breed pretty rapidly and they just eat everything like possums, probably rats is another good description for them as well," William Anaru from the Te Arawa Lakes Trust told Newshub. 

Brown bullhead catfish were discovered in Lake Rotoiti three years ago before the population exploded and spread quickly into neighbouring waterways.

Locals have refused to let them get out of control, with the Te Arawa Lakes Trust assembling more than 450 volunteers to combat their growth.

"They have a lot of love for our lakes and they're very environmentally minded, a lot more than I was as a young fella growing up around here," Anaru said.

In just two years, volunteers and contractors have managed to catch 68,000 catfish - and the efforts are paying off.

"Same time last year we'd catch around 200 per net, but overall it's an 18 percent decline in catch rates since last year," he explained.

The decreasing catch rates are a positive sign that the population is in decline.

Catfish prey on small native fish and their eggs, stir up sediment and compete with freshwater crayfish for food.

They can survive for up to four days out of water, meaning they can hitch a ride on boat trailers and spread widely.

"It's really important for boaties and other people who use the lakes, if they're travelling between waterways, that they're doing the check, clean and dry prior to going into the lakes," Greg Corbett from Bay of Plenty Council Biosecurity told Newshub.

A community can make a difference, but it is taking an army to get rid of these gilled pests.