This study of Murray cod (Maccullochella peelii peelii) movements in a large lowland river in south-eastern Australia indicated that the species was not sedentary, but undertook complex movements that followed a seasonal pattern. While there were sedentary periods with limited home ranges and high site fidelity, Murray cod also under took larger movements for considerable portions of the year coinciding with its spawning schedule. This generally comprised movements (up to 130 km) from a home location in late winter and early spring to a new upstream position, followed by a rapid downstream migration typically back to the same river reach. Timing of movements was not synchronous amongst individuals and variation in the scale of movements was observed between individuals, fish size, original location and years.

A 2 year (2000)(2001) radio-tagging study was undertaken to investigate the movements of 51 golden perch Macquaria ambigua in the Murray River at Nyah in north-western Victoria, Australia. During the winter of both years, golden perch did not undertake movements >5 km and displayed strong home range fidelity. In the first year of the study there was an increase in the distance of golden perch movement during late spring which coincided with increasing water temperature and river discharge. Nineteen golden perch were tracked during this period, of which 10 travelled downstream between 11 and 290 km. Seven of these fish moved to an area below the junction of the Murray and Wakool Rivers. Five golden perch travelled upstream between 13 and 35 km, four of which travelled to an area around the junction of the Murray River and Speewa Creek. The remaining four golden perch undertook localized movements of <5 km. Many of the long distance movements undertaken in spring 2000 were rapid and 53% of these golden perch returned to within 3 km of their release locations, indicating homing behaviour. Given that the rapid movements of golden perch in spring coincided with the known spawning season of this species, these long distance movements may be associated with reproductive strategy. # 2005 The Fisheries Society of the British Isles

In early 2003 a series of large, wildfire-related sediment slugs occurred in streams in the south-eastern Australian alpine region. Back-pack and boat-mounted electrofishing were used to measure changes in riverine fish fauna after one particularly large sediment slug which started in an upland stream and then travelled downstream through 200 km of third and fourth order stream. Twelve impact sites and eight control sites were surveyed where there were previous data on fish populations. The sites were surveyed directly after the sediment slug had passed and then 12, 24 and 36 months after. Immediately after the sediment slug, fish abundances fell by between 95-100% at four impact sites in the upper reaches of the study area, primarily due to the effect of low-dissolved oxygen levels. Twelve months later fish numbers were still decreased in the upper catchment but showed signs of recovery after 24 months. Further downstream, where water quality was not as severely affected by the sediment slug, the effects on native fishes were less apparent. The circumstances of these events represented a unique opportunity to obtain baseline data regarding the effects of post-fire disturbances on fish, and their time to recovery. If fire were to occur in catchments where endangered species exist, our results suggest that actions such as translocation may be required to ensure the long-term survival of threatened species.

The Australian irrigation industry diverts significant volumes of water from our rivers, and as such, may also divert and entrain riverine fish. Although it is widely acknowledged that our native fish fauna have been greatly affected by a variety of anthropogenic changes, little is known about the extent or significance of fish entrainment in irrigation systems. This paper presents results from a preliminary investigation into the diversion of fish into irrigation channels undertaken in the Goulburn-Murray Irrigation Network, Victoria, Australia. The case study and our knowledge of the life-history strategies of the Basin's fish fauna suggest that the loss of native fish into irrigation networks may be a substantial problem, which, up until recently, has been largely ignored. We strongly suggest that the impact of diversions on native fish populations requires urgent further investigation and quantification, through the cooperation of water management authorities and fish biologists.

Otolith chemical analyses (proton-induced X-ray emission and laser ablation inductively coupled plasma mass spectrometry) were used to examine patterns of diadromy in Australian grayling Prototroctes maraena collected from three rivers in south-eastern Australia. Concentrations of Sr:Ca and Ba:Ca were measured in the sagittal otoliths of 25 fish and in water samples collected on two occasions from multiple sites within freshwater, estuarine and marine reaches of the rivers. The results provide evidence of marine residency during the juvenile phase, with high Sr:Ca and low Ba:Ca in the inner region of the otoliths that were consistent across all three rivers. This general pattern was apparent for all individuals examined, suggesting that diadromous migration may be an obligate aspect of the life history. The chemical signatures of the outer regions of the otoliths were distinct between the three rivers, whilst there was no difference in the inner regions of the otoliths. This suggests that juveniles from different rivers may reside in a relatively homogenous chemical environment, such as the sea, and populations in coastal Victorian rivers may share a common marine recruitment source. #