"This equates to 53 fish in this size class per kilometre in the mid stretches of the river, compared with 36 last year."
Large numbers of juveniles were also recorded this time, pointing to a successful spawning over the past winter.
"Trout numbers were very high in both the Opato Stream and the middle reaches of the Waioeka River in the four kilometre stretch below the confluence with the Opato Stream."
Given the warm low flows at present, those areas with higher water flows, and rapids which oxygenate water, provide good refuge and cover for the fish.
The temperature of the river was measured at 20 degrees Celsius, "very comfortable for humans to swim in, but trout find the temperature a bit warm so go looking for some cooler water."
The upper Waioeka River produced a lower count of fish than in recent years, due to the particularly low and clear water conditions, forcing fish back to more comfortable habitat, Mr Osborne added.
The lower reaches of the river were almost devoid of fish except for the occasional large brown trout living in the deepest of the pools.
But Mr Osborne said that once the water temperatures cooled and more flow entered the river following rain, the trout would spread throughout the river.
Mr Osborne said the river had large growths of filamentous algae over the rocks at the moment caused by the low warm conditions which can be a real nuisance to anglers, as it can get caught on hooks with nearly every cast.
"We really need some good rain to flush it away".
Anglers are also reminded to Check, Clean and Dry between waterways to stop the spread of aquatic weeds and pests.