The decline of the endangered Macquarie Perch, Macquaria australasica, has been attributed partially to habitat modification, which can cause the mortality of fish in numerous ways including increased predation. Cotter Reservoir, the most downstream of three reservoirs that provide water to the Australian Capital Territory, has provided sufficient habitat to sustain a population of Macquarie Perch. However as drought conditions continue throughout Australia the expansion of Cotter Reservoir is imminent and existing habitat, specifically beds of emergent macrophytes, will be lost. Emergent macrophytes in Cotter Reservoir have been found to be an important part of the habitat for adult Macquarie Perch, providing protection from predators, in particular cormorants. This study will examine the behaviour of Macquarie Perch and cormorants using methods including radio-telemetry and observation. Experiments will be conducted to examine changes in habitat use by Macquarie Perch and the rate of predation by cormorants upon Macquarie Perch when emergent macrophytes aren’t available. Changes in rates of cormorant predation with the addition of artificial habitat will also be explored. As well as identifying the predator-prey dynamics of cormorants and Macquarie Perch it is hoped that this study will provide information that will ensure that cormorant predation and habitat loss do not combine to cause the demise of this population.