Fishways in Mainland South-Eastern Australia
Proceedings of the International Symposium on Fishways '90
The restriction of fish movement along the streams of south-eastern Australia is an important planning and management issue. All 66 indigenous freshwater fishes in this region require some degree of passage along streams. Fish movement has been impeded by many dams and weirs, built in response to a climate of low and variable rainfall. While 47 fishways have been built in the region, most have been ineffective. A particular difficulty in providing fish passage in coastal systems is the abundance of catadromous and amphidromous fishes, whose young must migrate upstream past barriers. Recent research in New South Wales has evaluated the swimming abilities of four native fishes in laboratory models of vertical-slot fishways. This type of fishway has proved to be well suited to both Australian conditions and the fish species tested. The research has provided the flow criteria needed to design and construct five new vertical-slot fishways effective for passing native fishes. Field evaluation of these fishways is proceeding. Preliminary investigation of the remedial installation of Denil fishways into the excessively steep (up to 1 on 2.75) channels of older pool-type fishways has been encouraging. Future research will test this low-cost remedy in other structures and with a range of other fish species.