Catfish set for acoustic tags in bid to control pest population

CAUGHT: A catfish caught when the incursion first occurred. PHOTO/ SUPPLIED

Acoustic tags will be implanted inside catfish at Lake Rotoiti as the Bay of Plenty Regional Council spends hundreds of thousands of dollars trying to bring the pests under control.

Brown bullhead catfish were first confirmed in the lake in March 2016.

Two catfish were seen and one caught during weed harvesting operations in Te Weta Bay.

Regional council biosecurity team leader Shane Grayling said each year the council spent more than $200,000 on control, surveillance, and research on the catfish population.

About 4693 catfish have been caught in Lake Rotoiti to date, including the containment of a spawning event when 1227 juvenile fish were caught (within the cordoned area) from a single net, he said.

"Control of catfish is done via the systematic setting of fyke nets; these are live capture nets which are baited with sardines and mussels."

As well as the fyke nets, the council was also working on an acoustic trial.

"Research currently under way includes acoustic trials focused on tracking the movements of catfish around Lake Rotoiti.

"Thirty catfish will have acoustic tags implanted inside them. Their movement will be tracked for up to one year by a series of receivers strategically placed around the lake."

Data from this study will show seasonal movements and allow more informed targeting of catfish, Grayling said.

The council has also agreed to fund the development of eDNA.

"This technology is highly regarded by the Lakes Water Quality Society who have been strong advocates for BOPRC to invest in its development. BOPRC have agreed to fund it, currently waiting for the University of Waikato to provide a proposal including costs.

"DNA extracted from water samples can determine if a particular species is present in that water body."

Nets have also been set in lakes Tarawera, Rotorua, Rotoehu, Rotoma, Okataina and Okareka.

"No catfish have been caught in any of these lakes so we are hopeful that we have stopped the spread of catfish for now and we're continuing to explore options for eradication.

"If you see anything fishy, please call us on 0800 STOP PESTS (0800 786 773) or send an email to STOP.PESTS@boprc.govt.nz."