The introduction of non-native species to many parts of the world is increasing and continues to be a major concern amongst scientists. My objective was to examine competition for space and other resources between native and introduced salmonids. Through physiological telemetry and behavioural observation, the movements, energy expenditure, and interactions within and between spawning feral Chinook salmon and released native Atlantic salmon were measured in Bronte Creek, a tributary of Lake

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... rio. By combining telemetry and visual observations, the frequency, duration, and energy cost of all behaviours (including routine behaviours) were determined. The data were used to construct an energy budget for each species, to identify additional energy costs due to interspecific interactions, and the degree to which the added cost may influence reproductive success for both species. Chinook salmon were observed to be dominant to Atlantic salmon on the spawning grounds and had the highest average daily energy expenditure, 7090 cal/kg/day. Atlantic salmon spent most of their time hiding under rocks or holding in areas where Chinook salmon were not present and females had an average daily energy expenditure of 2703 cal/kg/day. Male Atlantic salmon consumed more energy on average per day than did female Atlantic salmon, 3771 cal/kg/day. However, Atlantic salmon remained on the spawning grounds for a greater amount of time and so were observed to conserve energy. If the frequency of interactive behaviours between the species were to increase then spawning may be compromised in that less energy may then be available for reproductive success. Neither of the species were seen to spawn in this study. This may be related to the additional energy costs of interspecific competition or to the presence of an introduced species on the spawning grounds of a native fish species. Results of this study may also be applicable to potential interactions between native Chinook salmon and farmed Atlantic salmon in British Columbia.