Canterbury anglers blame irrigation companies for a drop in salmon numbers.
Angler Paul Hodgson said salmon numbers were down because fish screens - supposed to stop them getting sucked in to irrigation canals - did not work.
The Rakaia River in Canterbury. Photo: Supplied
"There is no incentive for the farmers to make it work, there's no requirement from Environment Canterbury (ECan) to make it work," he said.
"The Rangitata River is the one river where we do have the scientific studies, we do have the conservation order on it, we have raised complaints, but nothing's changed."
On the Rangitata River up to 30 percent of juvenile salmon were drawn into irrigation canals, injured or died as they moved through fish screens.
The impact on fish stocks was noticeable, Mr Hodgson said.
He voiced his concern on behalf of anglers at a regional council (ECan) meeting today.
"At the mouth of the Rangitata River they might get 100 fish for the season, maybe 150. So your chances of catching a salmon this season, I would think you'd be better off going to Lotto and buying a ticket," he told RNZ News.
The council should ensure the screens worked and stop putting farmers' interests above those of recreational users, he said.
"There's 20,000 odd anglers in Canterbury. If they don't tell their wives, they probably spend about $1000 every season, it would be millions of dollars that it's worth to the economy."
Smaller fish clogged up the irrigators, he said.
The screens killed native fish, such as the critically endangered Canterbury mud fish, councillor and fresh water ecologist Lan Pham said.
"I think it's always been put in the too hard basket because we simply don't have the technology and the infrastructure to actually support effective fish screens, that's just a fact.
"We know... there is mortality associated with the fish screens, but we need to figure out a solution."
A 2014 report from ECan, Niwa and Fish and Game recommended ways in which Canterbury's fish screens could be improved.
Councillors asked staff to report back on what action, if any, had been taken.
