"Rotoiti 2-year-olds (the size most commonly caught at opening) were slightly heavier," Mr Osborne said.
The average size was 49cm and 1.52kg.
"The best fish came off Rotoiti weighing in at 5.5kg but there were some unconfirmed rumours of a similar fish caught on Okataina."
Both lakes had seen good growing conditions for the fish, he said.
On Lake Tarawera the fishing had been hard with fish size down slightly compared with the 2014 opening.
"We expected the fish to be smaller as a consequence of tweaking our staggered release strategies, which meant some of the fish had been in the lake for up to three months longer than others," Mr Osborne said.
The growing conditions in Tarawera had also been poor over the past year.
"Next year, with further tweaking of this strategy, we are hoping to see better fish from all the lakes. "
Mr Osborne said the Rotorua lakes provided "lots of options" for anglers, and if the El Nino weather pattern kicked in as predicted and produced some still warm summer days, the shoreline fishing in particular would be "going off".
Anglers are reminded that Lake Rotorua has the highest catch rate of the region's lakes.