Biological catfish control considered in Rotorua lakes

A new biological control method is being considered for the eradication of Brown Bullhead Catfish in Lakes Rotoiti and Rotorua. Photo / File

The secret to the eradication of catfish in Lakes Rotoiti and Rotorua could be the introduction of more catfish.

A biological control method being considered by the Bay of Plenty Regional Council and Te Arawa Lakes Trust involves releasing sterile male catfish into a water body to disrupt the successful catfish reproduction by causing catfish eggs to be left unfertilised.

The goal of eradicating Brown Bullhead Catfish in Lakes Rotoiti and Rotorua has been given a boost with investigation into the new biological control method.

Bay of Plenty Regional Council biosecurity manager Greg Corbett said the preliminary investigations into using the control method showed there was strong potential for catfish biological control in the Rotorua Te Arawa Lakes.

"It's early days and while it has been used successfully overseas, at this stage the focus is purely on investigating the method further and determining how it could be applied in Lakes Rotoiti and Rotorua," he said.

"We have a good base understanding of the behaviours and impacts of catfish following the completion of six separate research projects in the last two years, so investigating the viability of biocontrol as a long term solution for catfish population control is a natural next step."

Te Arawa Lakes Trust environment manager Nicki Douglas said the application of mātauranga māori would be an integral part of the project.

"We know that catfish are having a devastating effect on kōura and other taonga species," she said.

"Including mātauranga māori-based research into this work will ensure that the research, implementation and monitoring of biocontrol incorporates kaupapa Māori assessments in decision making."

NIWA has already completed an initial feasibility study of biological control of catfish and modelling has indicated that suppression or even eradication of the species might be possible.

Biological control does not involve genetic modification and the activity is regulated by multiple central government agencies in New Zealand.

"Ultimately, the long term health of the Rotorua Te Arawa Lakes and its freshwater biodiversity is the top priority for everyone involved," Corbett said.

Douglas reinforced that the role of the Te Arawa Catfish Killas would continue to be crucial in the future to control catfish numbers.

"Biocontrol takes time and the incredible mahi of our Catfish Killas will be needed for a long time yet," she said.

Next steps for the project involve proof of concept work in a laboratory-based environment, working with regulatory agencies to determine permitting requirements, and commissioning of post-graduate research projects.

Engaging with Te Arawa hapū and iwi as well as community consultation throughout the Rotorua Te Arawa Lakes area will be an integral part of the project development.

For more information on catfish and the biocontrol project go to www.boprc.govt.nz