Assessment of the Outcome of Eight Decades of Trout Stocking in the Mountain National Parks, Canada

Abstract

The majority of the 1,464 lakes in the Canadian mountain national parks (22,376 km 2) were devoid of fish prior to the 20th century, and those lakes that supported fish populations were usually dominated by either mountain whitefish Prosopium williamsoni or longnose suckers Catostomus catostomus. From the early 1900s to 1980, about 305 lakes were stocked with either cutthroat trout Salmo clarki, rainbow trout Salmo gairdneri, brook trout Salvelinus fontinalis, or a combination of these. Results from fisheries surveys conducted primarily in the 1970s and 1980s indicated that, for lakes originally barren of fish, the probability of either rainbow or cutthroat trout (referred to as Salmo) species or brook trout becoming established was directly related to the size of the lake outlet. When Salmo and brook trout were stocked into lakes that were suitable habitats for both, brook trout displaced Salmo from lakes with small outlets but not from lakes with large outlets. When mountain whitefish, longnose suckers, and lake trout Salvelinus namaycush were present in mountain lakes, they prevented colonization by or restricted the population size of Salmo. Mountain whitefish and lake trout had a similar effect on brook trout, but Salmo and longnose suckers had no obvious effect on populations of brook trout.