A joint operation between several agencies and iwi has targeted the dozens of goldfish lurking in Whakatane's Sullivan Lake.
Highly visible fish, most believed to be goldfish, have been in the lake for years. Numerous attempts have been made to confirm whether other species are also present.
When the lake level was lowered to replace retaining walls and remove sediment, Bay of Plenty Regional Council land management officer Dave Paine saw an opportunity to catch more of the wily fish while the population was in a more concentrated area.
He organised a day's fishing operation with Ngati Awa iwi representatives, Whakatane District Council and Department of Conservation, which is responsible for managing koi carp. Several contractors dropped other work to provide equipment and expertise and an eel fishing expert.
The hunters started the day with a karakia from Whakatane councillor Pouroto Ngaropo and the team went to work using a combination of gill-netting, seining and electric fishing to catch about 40 fish for further identification.
"The fishing was extremely difficult because the layer of soft bottom sediments made wading through the lake dragging nets challenging and sometimes exhausting," Mr Paine said.
All of the fish caught appeared to be feral goldfish, not koi carp, and they may well have got into the lake through people disposing of the contents of home fish tanks. In the lake environment they grow much bigger than the domestic variety confined in a bowl, and compete with other species for food.
Positive identification of the fish without capturing them was very difficult, he said.
"Feral goldfish are known to exist in Sullivan Lake and many other lakes around our region, including many of the Rotorua lakes. They are easily mistaken for koi carp but don't affect the environment as badly as koi carp," he said.
While the Regional Council doesn't actively manage feral goldfish populations, koi carp are listed as an exclusion and eradication species, and the council works with landowners and DoC to control known populations and identify where they are present.