Movement of introduced Goldfish Carassius auratus: implications for control

Goldfish Carassius auratus has been widely introduced across the globe and feral populations are known to have considerable ecological impacts within the receiving environments. Despite centuries of domestication and its current widespread distribution, there is a dearth of information on the spatial and temporal movement patterns of this species, which limits the understanding of the impacts of introduced populations and hampers the development of effective control measures. The current study examined the movement patterns of an introduced population of C. auratus in a regulated south-western Australian river using passive acoustic telemetry. The species had a high residency index within the array (mean 0.64 ±0.06 S.E.). Mobility was high, with the mean minimum distance travelled within the array for individuals over the study period equalling 81.5 rkm (linear river kilometres, which was the sum of the distances of all movements between receivers and an underestimation of actual distances travelled); with one fish moving 231.3 km (including 5.4 km in a 24 hour period). Importantly, C. auratus displayed notable seasonal movement patterns including a clear shift to certain habitats during its breeding period; with most individuals being detected in an off channel wetland during that time. The results of this study have considerable implications for developing control programs for the species, such as targeting connections to off-channel lentic systems during the breeding period. Finally, the presentation will touch on the subsequent study that tracked the movements of Black Bream in the heavily modified estuary habitat downstream of the Goldfish acoustic array that aimed to refine the operation of floodgate barriers