Coho salmon Oncorhynchus kisutch were genetically altered to produce growth hormone without regulation, causing them grow 11 times larger (on average) than control fish after 14 months. This technology has potential benefits for the aquaculture industry, but the environmental risk associated with the escape of transgenic fish into the wild is not known. To partially address this issue, we experimentally investigated how well transgenic salmon survive when given a choice to consume food in a predator's presence. If transgenic salmon are to retain their growth advantage, we predict that they must also be more effective at competing for food than wild salmon and be willing to suffer higher mortality rates when foraging. The relative competitive abilities of transgenic and control salmon at two different ages were tested with an unequal competitors ideal free distribution. A larger proportion of transgenic salmon fed within the system, although they were not overrepresented at a higher-quantity food source. When feeding in the presence of a predator, there was no measurable difference in mortality rates between transgenic and control salmon at both the fry and parr stages. These data indicate that, under the limited environmental conditions we tested transgenic coho salmon are at least competitively equal to control fish and do not suffer higher rates of mortality to acquire food resources and maintain their enhanced growth.