Been traveling around the North Island recently and tried spin fishing for trout at different locations.
In general it seems there are a lot of trout and they especially seem to like lures with red in them.
My best fishing was in the Whanganui River, near Taumarunui. We were getting bites on every third cast and nice big fish. The Rainbow trouts in this area had a slight muddy taste - the brown trouts tasted fantastic.
The Taupo region has not much to offer for spin fishers during winter. Only a few places open - everything else is fly fishing only. But there a good chances to catch nice trout at the Tokaanu tail race.
The lakes around Rotorua seem to produce some really big Rainbows as well. They come pretty close to the shore and taste fantastic.
If people concentrated on the really important things in life, there'd be a shortage of fishing poles.