19 December 2018

The discovery of catfish in Lake Rotorua wasn’t the surprise that the Bay of Plenty Regional Council staff were hoping for this holiday season; however that’s what they got on Tuesday when six catfish were caught near Mokoia Island during biosecurity surveillance work.

This is the first time the pest fish has been found in Lake Rotorua. Regional Council Biosecurity Manager Greg Corbett said he’s devastated by the discovery but his team won’t be giving up on trying to control the pest fish.

“The next step will be to carry out more surveillance to determine the extent of the infestation. Once we know what we are dealing with, we will work with our partners to develop a plan of attack,” explains Corbett.

It is not yet known how the catfish got into Lake Rotorua, and while it is likely they got there by moving up through the Ōhau Channel, Mr Corbett said he can’t rule out humans giving them a helping hand.

“Catfish are like cockroaches and can survive in some pretty extreme conditions, including being out of water for up to 48 hours in summer. These catfish may have been hiding on someone’s trailer, boat or jetski. It is also common for pest fish and their eggs to hide amongst the weeds that people often neglect to remove from their gear,” explains Corbett.

With summer holidays officially starting this weekend, the lakes will be at their busiest, and the risk of catfish spreading even further is at a critical point, if lake users aren’t vigilant.

“A single catfish can lay up to 10,000 eggs so it doesn’t take many of them to spoil a lake, said Mr Corbett.

He’s asking lake users to help stop the spread of catfish and other aquatic pest by taking just five minutes to do three simple things. Before you leave a lake, waterway or river, make sure you:

  1. Remove all weeds from your boat trailer and gear. Small catfish and their eggs could be hiding amongst the weeds.
  2. Empty any lake water or ballast you may be carrying. This is especially relevant to those water-skiing and wakeboarding.
  3. Don’t leave your trailer in the water. You’d be surprised at how quickly a catfish can become a stowaway, so make sure you only have your trailer in the water when loading or unloading your boat.  

Additional information:

  • What is it? Brown bullhead catfish, common in the Waikato River system however a new pest to the Bay of Plenty.
    Why they are a pest? Catfish predate on native species such as koura as well as trout and their eggs. They also lower water quality by churning up mud.
  • What work has been done to stop the spread? Bay of Plenty Regional Council has netted 53,478 catfish in Lake Rotoiti since March 2016. They are also funding research by NIWA and the University of Waikato to find new surveillance methods and eradication tools to stop the spread of the pest.
  • The Regional Council and Te Arawa Lakes Trust are also working with community groups and locals to raise awareness and start a community netting programme in Lake Rotoiti.