Rare fish found in Lake Ōkāreka stream

Rare fish found in Lake Ōkāreka stream

For immediate release: 31 August, 2010

A rare native fish population known as koaro has been discovered in a tributary stream of Lake Ōkāreka

The native galaxid fish species is now rare in the Rotorua lakes, Bay of Plenty Regional Council environmental scientist Matt Bloxham says.

“Koaro have probably declined in the Rotorua lakes for a variety of reasons. Reductions in water quality in some of the lakes and habitat changes have taken their toll, but the introduction of trout and smelt to the lakes has brought about a dramatic and sustained decline in koaro numbers.”  

The Regional Council, Department of Conservation, NIWA and Te Arawa Lakes Group have been working with local landowners Chris and Helen Russell to create habitat for koaro in their small stream on the western side of the lake. 

“Although once present in the Russell’s stream, none have been found here recently, nor in the tributary on the southern side of the lake, so to find koaro in a stream we didn’t know existed until quite recently is pretty exciting,” Mr Bloxham said.

Keen native fish enthusiast Mike Goodwin had a hunch that the stream might contain some surprises, and in early July he led a team of scientists from the council, DoC and NIWA and a Waiariki Polytechnic student to the site. Fish traps were laid that night, and found the fishy rarity.

“We didn’t have great expectations that the stream would contain koaro, because although there is plenty of habitat for koaro there, the stream appeared likely to support trout. A total of 34 koaro were found and no trout. This is the largest known population of any of those being contemplated for remediation, and it represents the only healthy tributary population in Ōkāreka. 

Mr Bloxham said while there were numerous shallow spring heads that would provide refuge for koaro if trout found their way into the tributary, the population was still highly vulnerable. 

“We’re looking to create habitat in other former strongholds to help spread the risk. We are lucky having landowners like the Russells to work with and our habitat restoration work in their stream is beginning to bear fruit. Pools have begun to form and are being used by small trout where previously there were none. While trout are not the species we’d hoped to find, with a little more work we hope koaro will re-establish in the stream,” he said. 

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