The Lake Tarawera trout stock has received a healthy boost with 1000 yearlings released into the water.
Eastern Fish & Game released the 9-month-old fish reared at the Ngongotaha Trout Hatchery into the lake yesterday. It was the first summer release as part of its liberation programme.
Officer Lloyd Gledhill said there was a gap in the trout's life cycle which, along with the unique volcanic based lakebed conditions, produced low spawning numbers.
"It would probably be one in a thousand native spawning so without the release the trout numbers in the lake will diminish right around," Mr Gledhill said.
"The fish were raised at the hatchery and were derived from top Tarawera fish, mum and dad came here so for them they're coming home."
Half of the released fish had yellow tags attached and the other half had their fins nipped so officers could recognise them. The release from a trout tank truck took about two minutes with many tourists standing on the jetty watching and recording the action.
"We are asking those that catch one with a tag on to tell us when it was caught, the length and where it was caught," Mr Gledhill said.
Fishers who send the trout details to Fish & Game will be sent specific information about the fish that was caught and will be in to win one of 25 fishing licences.
Another 500 fish will be released into Ruato Bay at Lake Rotoiti today with the next scheduled liberation release next month.
Eastern Fish & Game officers have also completed a fish-spotting mission in the Eastern Bay of Plenty - and sighted some "encouraging" numbers.
'Drift diving' is an activity in which a small group of wetsuit and snorkel-equipped officers swim down river in formation, counting trout along the way.
Officer Matt Osborne said this was the third year running staff had monitored the Waiokea River using drift dive counts.
"We monitored three 500m-long stretches in the Opato Stream and eight in the mainstem Waioeka River last week.
"This year we counted 291 medium to large fish across all our sites - well up on last year," Mr Osborne said.