TRM Facebook on Sunday displayed the memorials for introducing Rainbow trout to NZ. They generated so much interest we thought they deserved to feature for the TRM Daily Report today. They should be self explanatory with the top images from Auckland Domain and the lower Tapapa inscription from Whites Road near Putaruru. There are so many interesting stories of the struggles by the various acclimatisation societies to introduce trout to the Taupo Region with four – from Wellington, Hawkes Bay, Auckland and Taranaki all claiming Taupo as their “jewel in their crowns” and releasing “Steelhead” (Rainbow) trout from different locations on the USA West Coast. Each province introduced their version in different tributaries to create one of the best wild trout fisheries in the world. That is why we still see slight differences – darker and lighter colours etc. in the surviving strains of Taupo trout.
Following info pinched from NIWA website:
Rainbow trout
Oncorhynchus mykiss (Walbaum, 1792)
R.M. McDowallRainbow trout are native to the westward draining rivers of North America and also to the Kamchatka Peninsula on the western side of the Pacific Ocean. Stock introduced into New Zealand were brought from North America as early as 1883. Although they were not as easy to establish as brown trout, self-sustaining populations of rainbow trout are now widespread in New Zealand and form the backbone of the popular and highly valued fisheries that occur in the lakes and rivers of the central North Island. They also support fisheries in many of the lakes along the eastern flanks of the Southern Alps in the South Island.
Like other salmonids, the colour pattern of rainbow trout is variable. Lake-dwelling fish are generally uniformly silver with small, darker spots along the back, mainly above the lateral line. The backs of river dwelling fish are often more olive-green, and the red band, or rainbow, along the lateral line more prominent. When rainbow trout move into rivers and streams for spawning, this band intensifies in colour, and red slashes may occur on the cheeks and in the folds beneath the lower jaw.
Rainbow trout can be distinguished from brown trout and Atlantic salmon by the presence of dark spots on the caudal (tail) fin, and from brook char and mackinaw by the absence of pale spots on their sides. Rainbow trout have a short-based anal fin compared to a long-based anal fin on sockeye salmon. Spawning chinook salmon also develop a red flush along their sides and hence can be confused with rainbow trout. However, chinook salmon have black gums whereas the mouth of rainbow trout is pale in colour.
Most rainbow trout migrate to their spawning grounds, with both lake and river dwelling fish moving upstream to suitable locations, often in small tributaries. Here they may congregate in large schools just prior to spawning. In lakes without suitable spawning tributaries, spawning can occur along the lakeshore. The main spawning season for rainbow trout is June and July, but the season can be extended to October in some lakes, especially those in the colder regions of the North Island.
Although there are no sea-run populations of rainbow trout in New Zealand (usually very large fish known in North American as steelhead), fish 500–600 mm in length and 2–3 kg in weight are the norm in most New Zealand populations. In lakes regarded as trophy fisheries, fish of 4–5 kg are caught regularly.
And another local history:
A brief history of trout fishing in and around Lake Taupo.
Turangi, 40 minutes south of Taupo town, is known as the “Trout Fishing Capital of New Zealand” and every year thousands of tourists flock to the Taupo region to get in on the action.
But sport fishing on, and in the streams and rivers around, Lake Taupo is an introduced sport. The lake was something of a disappointment to early European settlers, including the Armed Constabulary (AC), because it did not possess a variety of native fish. Instead, there were just koaro and common bully. Fish of both species were comparatively small, though they were used a resource by Maori. There was also freshwater crayfish.
In 1873, Inspector Morrison, in charge of the AC at the time, released golden carp in the lake. While they acclimatised and still remain, they never established a significant presence.
The Golden Carp were followed by Brown Trout, released into the lake in 1885, 1892, and 1894.
Brown trout were released when, not daunted by the lukewarm success of the Golden Carp, the AC’s then commanding officer Major David Scannell (later Judge Scannell) set up a Brown Trout hatchery about 1885, on the outlet from the lake. About the same time, Daniel MacDonald set up a hatchery on his property, on the Napier-Taupo road. Young fish from this hatchery were released to streams 
on the property, the Rangiteki River and tributaries on the eastern side of the lake.
In addition to these efforts, Wellington sent Brown Trout ova to Taupo in 1894 and ’95, which were tended at a new hatchery in Nukuhau.
From here, fish were released to streams feeding into the lake as widely as possible. Sam Crowther, who drove coaches between Taupo and Tokaanu, is said to have released young trout in every stream he passed. These trout took to their new home like, well, fish to water. Within two years trout could be seen in all waters on the lake’s eastern side. By 1901 a local hotel was promoting “Splendid Trout Fishing” in the Tongariro River. As the fishing fame of the Lake and its streams and rivers increased, accommodation and associated services sprung up to cater for the visiting anglers, including the now world famous Huka Lodge.
Rainbow Trout followed the introduction of Brown Trout, released into the lake between 1900 and 1906. Common smelt were later introduced as a source of food for the trout when their size and quality began to decline.
Lake Taupo remains one of the truly wild fisheries in the world, with no need to replenish the supply with hatchery produced fish. While the Department of Conservation-managed Tongariro Trout Centre does have the capacity to produce large numbers of young trout, it currently only produces a few, mainly for the children’s fishing pond at the centre. It has never been used to support or supplement the supply of wild trout in the lake and its tributaries, though fish from the Centre have been used in a series of one-off releases for scientific purposes. However, the hatchery is maintained to be ready to produce large number of trout if needed, if for example a natural disaster or some other event put the wild trout stock in jeopardy.
While trout are classed as sport fish and can’t be bought or sold in New Zealand, the money spent on fishing-related products makes up a significant proportion of the hundreds of millions spent by tourists in the Taupo district every year. As much as 80% of Lake Taupo anglers are visitors, not locals.
As well as the native fish, and deliberately introduced trout and smelt, there have been goldfish and catfish found in the lake as illegally introduced pests.