Is the home range concept compatible with the movements of two species of lowland river fish?

1. Many studies of the movements of riverine fish have found that most individuals are sedentary and occupy very restricted home ranges. Recently, this 'Restricted Movement Paradigm' has been challenged and there is currently a need for tests of the home range concept as a theoretical basis for describing the movements of riverine fish. In this paper, I describe a radio-tracking study of golden perch (Macquaria ambigua) and carp (Cyprinus carpio) in the Broken River, Australia that aims to assess the home range concept as a means of describing the movements of these species. 2. A random movement analysis and a translocation experiment were conducted to test for site fidelity and home range occupation. Both golden perch and carp exhibited strong site fidelity and occupied restricted home ranges. Carp had larger total home ranges than golden perch, and both species had areas of concentrated use (core areas) within the home range. 3. Several golden perch and carp exhibited shifts in the locations of their home ranges during the study. To incorporate such shifts into a theoretical framework, a 'home range shift' conceptual model is proposed and the need to consider the temporal stability of site fidelity when describing home range movements is discussed.