The Kamloops Lakes Trout

kamloops lake rainbow trout

A Kamloops Lake rainbow trout.  Rainbows reach great sizes in the lakes of the Kamloops region, whose waters are rich in invertebrate foods.
Specimen study/watercolour

In 1812 the first white settlers of the western foothills of the Rockies and the plains and valleys of inland British Columbia established a fort settlement which they called Fort Kamloops. A few years later a nearby lake on the Thompson River was given the same name, Lake Kamloops. From this lake, and also from others in the same area including Adams, Kootenay and Shuswap-the early settlers caught large numbers of big silver trout.

So prolific were these fisheries that towards the end of the 19th century the Kamloops began to attract numbers of visiting anglers. In 1892 two visitors sent some specimen trout to Professor D. S. Jordan who gave the fish the name Salmo kamloopsii. This was during the days of the 'species splitters': today the trout of the Kamloops lakes are regarded as a variety of the rainbow trout Salmo gairdneri.

The Kamloops lakes are set in the midst of hills that rise to 6,000 feet. The valley floors are often too dry and windswept to support forest. Grassland and sage scrub predominate, though in marshy hollows and at the water's edge there are stands of willow, aspen and cottonwood. Stretching beyond is the forest, with fir, pine and larch at lower levels, and lodgepole pine and spruce on the higher slopes. The wooded hillsides retain water, providing a regular flow to the feeder streams in which the trout spawn. As the water slowly percolates through the rich soil it picks up large quantities of mineral nutrients which are carried by the feeder streams into the lakes.

The high level of nutrient salts makes the Kamloops lakes exceptionally productive. Water weed and plant plankton abound and support huge quantities of aquatic invertebrates; the trout grow rapidly. Sometimes, however, the very richness of these lakes results in the death of a proportion of the trout stocks. In summer, when the air temperature may exceed 35C, the bloom of aquatic plant life can result in bacterial decomposition that removes the bulk of oxygen from the water: a trout-kill then results.

In winter, when the lakes are iced over and oxygen from the air cannot diffuse into the water, the slow decomposition of dead plant material may similarly result in oxygen levels that are dangerously low. On occasions a lake may lose its entire trout population; but the stock is replaced naturally when young trout that have spent the first year or two of life in their natal feeder streams enter the lake.

The Kamloops trout breed in spring. Through the winter the lakes are locked in ice, and when the thaw comes the mature fish-usually four years of age or more-run the feeder streams or outflow. There in May they spawn and, in the majority of cases, die. The trout fry emerge in summer. Some move slowly through the stream to the lake, but others remain in the river, possibly for just one year, but in some cases for life. Those that enter the lake grow quickly before the ice of winter brings virtual hibernation.

The immature trout show very different growth rates in the lake and the river. By the age of two years a lake Kamloops will be at least ten inches long; a river trout much smaller. A two-year-old from Lundbom Lake was found to have grown to 14 inches, while a fish from the same spawning, taken from a nearby stream, was but 3 inches in length. Why do not all the trout fry migrate to the lake, where the feeding is clearly so much better than the spawning stream? Whatever the reason, the result is a reserve population in the stream that can restock the lake naturally should catastrophic deoxygenation wipe out the lake stock.

The size and abundance of Kamloops trout have made the lakes a mecca for anglers. There are tales from the early years of cowboys catching 300 fish in a day on the most basic tackle made from a willow stick with a piece of string tied to the end, and a single fly. There were also some massive trout. In 1932 one was taken from Jewel Lake that may have been the biggest trout ever caught: though its weight was not officially verified, it was reported as scaling 56 lbs. As recently as September 1977 a fish of 25 lbs. 2 oz was taken on dry fly from Kootenay Lake.

Decades of fishing pressure by 'sporting' anglers, commercial fisherman, and more recently huge numbers of visiting anglers, have taken their toll on the main Kamloops lakes. The effects of over-fishing have been exacerbated by mining waste polluting some waterways; spawning streams have also been damaged by erosion and silting due to deforestation of the river banks. The result is that for many years the Kamloops lakes have been unable to maintain their trout stocks by natural output.

Artificial hatcheries now produce trout for the major lakes, in many cases successfully. Other waters, especially lakes set high in the mountains, which the wild trout never colonized, have been stocked with Kamloops trout. However, some have been overstocked, with disastrous effects on the lake invertebrate populations and the trout themselves.The wilderness that was once a part of the Kamloops region is slowly disappearing as growing numbers of American, Canadian and European anglers despoil the lake shores. Along the shore of some of the more accessible lakes lie piles of rubbish-empty rusting food cans, beer bottles, plastic bags, discarded nylon fishing line, and general litter. From the lake comes a continuous drone of outboard motors and the wind drifts the stench of spilt engine oil and fuel. The Kamloops is, indeed, a wilderness in danger.