Large brood fish are taken back to the hatchery at Ngongotaha and their eggs form the basis of the breeding programme which raises hundreds of thousands of baby trout for release into lakes and rivers.
Anglers can also donate big trout for the hatchery if they catch one at the stream mouth by netting it so it is not handled, and dropping it into the front slot of the trap, which is just upstream of the mouth which is one of the most popular fly fishing spots on the lake at this time of year.
They should then call Fish and Game and let them know. The reason the largest trout are used for breeding is the same as farming; the best adults produce the strongest young.
Usually one of the three big lakes - Lakes Rotoiti, Tarawera and Okataina - will shine in terms of the quality of the trout, for this is the time of year anglers expect to hook the biggest fish of the season.
The mature trout, which are usually three years old, return to their natal streams as adults to spawn.
Fish and Game also operates a fish trap on the Ngongotaha Stream, which is the main spawning tributary for both Lakes Rotorua and Rotoiti.
The Rotoiti fish migrate through the Ohau Channel, and Sherburn said the channel was holding large numbers of smelt, which bodes well for the fishing.
"All of the lakes have healthy smelt populations, which is good to see," he added.
Three quarters of the trout recorded through the Ngongotaha trap were brown trout, and fish up to 4.6kg have been weighed.
The browns usually start their runs before the rainbows, and the same pattern occurs at Lake Taupo which also has a healthy population of brown trout, where they are also larger on average than their rainbow cousins.
All methods of fishing are working at present, and in Rangiuru Bay on Tarawera fly fishermen are doing well. It is a good time of year for fly fishing and harling the margins of the lakes, for smelt move into the shallows to spawn.
During the day deep trolling on the lakes will catch fish but it is not necessary to go as deep as in mid-summer when temperatures drive fish down.
Ruato Bay on Rotoiti is closed to boat fishing from April 1 out to 200 metres offshore, and fishing is restricted to fly fishermen wading the beach.
Other popular spots for fly fishing on the lake are the Pipe and Transformer at Hinehopu, the outlet at Okere and in the Ohau Channel as trout migrate through from Rotoiti.
The Ngongotaha, Utuhina and Waiteti Streams are the only streams where fishing is allowed in the streams themselves, and nymphing with small natural patterns or glo-bugs will be popular.
But the upper reaches are closed in certain sections, so a check on local regulations is important.
On Lake Okataina the Log Pool and the two streams at Rainers Bay will be worth visiting, but the stream mouths are small ones and there is room for only a couple of rods.
Saltwater
Snapper fishing has picked up around Auckland, with some good catches coming from the Motuihe Channel and around Rakino Island.
But as water temperatures drop the fish will move out to deeper water.
Top Tip
When trolling for trout with a lure like a cobra a fly can also be added to the line as an extra attractant.
The simplest rig is to add a small swivel about half a metre ahead of the lure, and the fly slides down and rests above the swivel. More fishing action can be found at GTTackle.co.nz.
Bite times
Bite times are 2.20am and 2.50pm today, and 3.20am and 3.55pm tomorrow.
