It got a boost from the scientific community after a government biologist gave the local trout its own distinct place in the register of recognized fish species — Salmo Kamloops.

It wasn't until the 1930s that further research showed the physical differences that led to the distinct species classification was caused by the environment, not genetics. As a result, the Salmo Kamloops species designation was quietly dropped from the books.

But the legend lived on.

Kamloops fisheries biologist Rob Bison said the Kamloops trout label describes the small-lake “phenotype” of the rainbow trout species. The Kamloops trout is also known as the Interior red-band trout.

Rainbow trout vary greatly in appearance, depending on where they are found and their age. Generally, rainbows have small heads with well-developed teeth on the roof of their mouth and no teeth at the base of the tongue.

They have an adipose fin — a small fleshy fin on the back behind the dorsal fin. There are black spots on the back, sides and fins. The adipose fin also has spots. Their colour is a silvery overall, often with an iridescent pink to reddish band along the lateral line. The tail is slightly forked.

Adults range in size from 30 to 75 centimetres in length, with a maximum of 90 centimetres. They typically weigh between one and seven kilograms.

“There is a huge variety of different forms of rainbow trout,” Bison said. “They can adopt all kinds of living strategies.”

The Kamloops trout is predominantly an insect eater, focussing its feeding efforts on source of food available in great quantities year round. They live primarily in small, landlocked lakes and have relatively short migrations, mostly to small spawning streams that fed the lake.

The Gerrard trout — the famous piscavores (fish eaters) of Kootenay Lake — are the rainbow heavyweights, capable of double-digit body weights. They have developed a unique relationship with the lake's kokanee. It's the young of the landlocked salmon that give the Gerrards a source of nutrition capable of generating such tremendous size.

There are local piscavores as well, though the stocks are not as well known, Bison said. They live mostly in Shuswap and Adams lakes and focus opportunistically on salmon stocks that pass through those bodies of water.

The coastal rainbows of the Lower Mainland also represent a unique phenotype and of course, there is the steelhead — the seagoing phenotype of rainbow trout that returns to freshwater to spawn.

It's the rich diversity of food in the saltwater environments that allows steelhead to gain more size than its inland counterparts, Bison said.

Thompson River steelhead are a unique and important variation of the rainbow trout species, he said. They are distinguished from other steelhead and rainbow phenotypes by the length of their migrations and the size and strength of the species.

Research has shown the Kamloops trout is more closely related to the rainbow trout of California than its counterparts on B.C.'s coast. It's now believed the rainbow trout came to the Interior as the glaciers receded more than 12,000 years ago, he said.

Then, the Kamloops-Shuswap-Nicola region was covered by a vast lake that drained not west to the coast, but south to the Columbia River. It's believed the California trout migrated north via the Columbia, settling in lakes across the Interior as the glacial melt water receded.

As the glacial bodies of water drained, separated from each other and became the lakes of today, the different rainbow trout phenotypes evolved and developed according the environmental influences present, Bison said.

One thing has emerged over the years — the rainbow phenotypes don't do well when moved from their own unique environments.

Despite the best intents, Gerrard trout have not shown a propensity to grow into behemoths when moved into Interior lakes. Without the kokanee fry to feed on, Gerrards fail to thrive, Bison said.

“Even though they have the genetic makeup to adapt to a lot of different environments, you can't expect them adapt immediately,” he said.

That's why the Kamloops trout has prospered and spread, as there are many small insect bearing lakes in B.C. capable of supporting its lifestyle, Bison said.

Most hatchery fish in B.C. are Pennask Lake trout, he said — classic red-bands of the stock that has spawned the Kamloops trout name.

Of course, the scientific debate rages still today about whether each of the varying phenotypes is worthy of a distinct species classification, Bison said.

“The whole business of what is a subspecies and what is not a subspecies is still being debated by taxonomists and geneticists,” Bison said. “It comes down to how you define a subspecies and right now, it's defined by genetics, not physical differences.”

That's why the Kamloops trout has prospered and spread, as there are many small insect bearing lakes in B.C. capable of supporting its lifestyle, Bison said.

Most hatchery fish in B.C. are Pennask Lake trout, he said — classic red-bands of the stock that has spawned the Kamloops trout name.

Of course, the scientific debate rages still today about whether each of the varying phenotypes is worthy of a distinct species classification, Bison said.

“The whole business of what is a subspecies and what is not a subspecies is still being debated by taxonomists and geneticists,” Bison said. “It comes down to how you define a subspecies and right now, it's defined by genetics, not physical differences.”