USGS Home
Contact USGS
Search USGS

Search fish passage bibliography

Mallen-Cooper, M. and J. H. Harris (1992). Fish migration in the Murray Darling system and the decline of the silver perch. Newsletter of the Australian Society of Fish Biologists. 22:41.

Upstream movements of fish were studies in the River Murray at Torrumbarry Weir (near Echuca), which is the site of a new vertical-slot fishway that has been operating since February 1991. Sites were established 35 km above the weir and less than 1km and 6km below the weir. These sites were sampled monthly with gill-nets and fyke-nets from January 1990 to June 1992. Upstream fish movement was inferred from differences in relative fish density between the three sites. Potentially migrating fish which entered the base of the fishway were also trapped each month, and the numbers and species of fish reaching the top of the fishway were monitored daily at other times. Large accumulations of fish were recorded below the weir, particularly of golden perch and silver perch. In these two species the dominant migrating group was immature sub-adults, which appeared to move upstream in response to a wider range of environmental cues than adults. Over 4500 fish used the new fishway in the first ten weeks of operation and most size-classes and species of fish moving upstream appeared able to ascend the fishway. Reproductively mature silver perch moved upstream during small increases in flow in summer. These flow events are severely affected by river regulation, which may explain the decline in silver perch indicated by commercial catches in the river and also supported by historical data of fish movements through weirs.