Seasonal Movement Patterns of Stream‐Dwelling Rainbow Trout in North‐Central British Columbia, Canada

Movement forms an important part of salmonid life histories, and although previous studies have largely concluded that the majority of stream‐dwelling salmonids are sedentary, the paradigm of restricted movement has been questioned by recent findings. We conducted a 3‐year study to examine the seasonal movement patterns of rainbow trout Oncorhynchus mykiss in three small, lake‐headed streams situated in north‐central British Columbia and to determine whether movement was related to environmental conditions. Two of the three streams were subjected to streamside clear‐cut logging during the second year. The trout in our study streams generally remained sedentary during the summer, autumn, and winter seasons for a period of approximately 1–2 years before undertaking long‐range (>372–607‐m) movements during springtime. These springtime long‐range movements were most closely linked to stream discharge, as they generally ceased with the onset of summer low flows (<10–20 L/s), but they did not resume in the autumn despite increasing flows. Links between movement patterns and stream temperature were less clear, as long‐range movements occurred over a wide range (0–30°C) of temperatures. The predominant direction of long‐range movements was lakeward. All three streams supported relatively large populations of resident trout during the summer and autumn months; densities of 0.4–1.0 trout/m2 were primarily associated with age‐0 to age‐2 fish. Our data provide insights into how the movement patterns and life history strategies of stream‐dwelling rainbow trout are intertwined, as well as how the timing of sampling efforts may be an important factor when assessing whether stream‐dwelling fish are sedentary or mobile.