Abstract
Radio‐tracking was used in monitoring the reintroduction of on‐grown 2 year‐old trout cod Maccullochella macquariensis (Percichthyidae) (a nationally endangered freshwater fish) in both a large and small upland river. Thirty‐six radio‐tagged M. macquariensis were stocked into a site in each of the Murrumbidgee and Cotter Rivers (Australian Capital Territory). Restricted dispersal occurred in both rivers, with both samples of M. macquariensis remaining within 5 km of the release site for the duration of the study. Mortality was rapid and 1 month after release 61 and 31% of the sample was alive in the Murrumbidgee and Cotter Rivers, respectively. In the Murrumbidgee River, complete mortality had occurred 6 months after release. An individual survived in the Cotter River until 7 months after release. Predation by cormorants Phalacrocorax spp. and predation or scavenging by the common water rat Hydromys chrysogaster were the probable causes of mortality. Predator‐assisted movement of radio‐tags by cormorants occurred in both groups and had the potential to confound interpretation of active dispersal movements.