A Canterbury angler is calling for action as numbers of a native fish species dwindle.
The Stokell's smelt can only be found in Canterbury but these days there are hardly any in the Rakaia river.
Stokell's smelt are small, they have a forked tail, a cucumber-like smell and are only found in Canterbury.
New Zealand Federation of Freshwater Anglers president Peter Trolove said he's been watching the species dwindle.
Trolove believes over-irrigation could be to blame.
"Through the sustained low flows associated with the irrigation we've had mud and sediment build up," he said.
Irrigation New Zealand says they're working collaboratively on a project to assess the impact irrigation may be having.
"I think what's concerning is that if there are multiple impacts on a species we need to really understand what they are so we can work together right across the spectrum to ensure we are doing what we can to protect our native species," Irrigation NZ Chief Executive Elizabeth Soal said.
Little is known about the species - DoC started surveying them again just three months ago.
"DOC is actually taking a stocktake. We are working with the other parties to come up with what is happening and comparing that with 1980s surveys to decide what to do," DOC freshwater ecologist Sjaan Bowie said.
"The trout basically survive on them and of course everything else survives on that it's all part of the food chain," angler Ken Hemingway said.
The native species is crucial to the ecosystem, and local anglers are hoping for the best.