Although trout fishing on the 200km of water races around the irrigation scheme was actively promoted, both the irrigation company and Fish and Game were keen to ensure juvenile salmon were not entering the irrigation scheme, Lower Waitaki Irrigation Company chairman Chris Dennison said.
If too many entered the scheme it could detract from recreational salmon fishing on the Waitaki River, he said.
"The study will start in the first week of September and run right through until April.
"We know a few have been seen."
Mr Dennison said the project had been planned two seasons ago, but poor conditions on the Waitaki River had meant Fish and Game had been unable to carry out the aerial redd nest survey that was needed to show how many salmon had spawned on the river.
He said the project would cost about $70,000.
Race manager Ross Bishop said traps had been installed at 18 sites along the scheme and a full-time staff member was employed to check three sites each night for the next eight months.
"The fish we are talking about are very small.
"Every fish caught will be weighed, measured and identified and all that will be passed on to Fish and Game."
Any trout caught in the traps would be released back into the race and any juvenile salmon released back into the Waitaki River, he said.
