Feels like home: homing of mature large-bodied fish following translocation from a power-station canal

Abstract

Fish translocation is a common method of conservation and fisheries enhancement. Monitoring post-translocation movements and migration provides useful information to inform translocation strategies. Three species of large-bodied fish (Yellowfin Bream Acanthopagrus australis, Luderick Girella tricuspidata, and Tarwhine Rhabdosargus sarba) impounded in a cooling water canal at a power station were translocated into the adjacent estuary (Lake Macquarie, New South Wales). Translocated fish were tagged with acoustic tags (n = 34) equipped with accelerometer sensors (providing a relative measure of fish activity) and released on either an artificial reef or a natural reef. In addition, 8 free-ranging Yellowfin Bream were captured and tagged on the artificial reef. Fish were tracked throughout Lake Macquarie on a dispersed array of 18 VemcoVR2W receivers, and on the artificial reef using a VR4-UWM Vemco Positioning System, for up to 11 months. Yellowfin Bream and Luderick rapidly migrated back to the power station, whereas Tarwhine remained near the release location. Translocated Yellowfin Bream showed divergent behavioural patterns to free-ranging Yellowfin Bream on the artificial reef, with much higher activity levels, elevated nocturnal activity, and different patterns of habitat usage, possibly reflecting divergent foraging behaviour. This study presents a rare example of non-natal homing to an artificial habitat in several large-bodied marine fish species. The role of low frequency sound in the homing of translocated fish, and factors contributing to the observed behavioural patterns are discussed. The presence of a homing signal which can facilitate return migration may decrease the efficacy of translocation efforts for adult marine fishes; however, these responses are species-specific and will require evaluation on a case-by-case basis.