Australian native fish have evolved to utilise a variety of habitat types to complete their life cycle, thus requiring unimpeded ‘migratory’ access along water at different times to survive and reproduce (e.g. by accessing food and shelter, avoiding predators, reducing localised competition, and finding mates). However, in Australia riverine connectivity has been severely disrupted by a legacy of instream barriers of many types (e.g. road culverts, weirs, dams, floodgates) to migratory fish that limit habitat and resource availability, and threaten the capacity of native species to adapt to changing environmental conditions (Pethebridge et al., 1998; Gehrke et al., 2002).
Fishways, also known as fish ladders or fish passes, are structures placed on or around constructed barriers (such as dams or weirs) to give fish the opportunity to migrate. Section 218 of the Fisheries Management Act 1994 (FMA 1994) enables the Minister for Fisheries to order fish by-pass provisions (i.e. fishways) to be provided at any weir or similar structure that is built, altered or modified. DPI Fisheries NSW has a Memorandum of Understanding (MOU) with State Water Corporation toprovide all necessary fish passage advice associated with structural upgrades and fishway related works at State Water’s dams, weirs and regulators in NSW.
State Water Corporation, through The Fish Superhighways Program developed in conjunction with the NSW Department of Primary Industries Fisheries, has constructed four fishways in the Lachlan Catchment. These fishways are located at Island Creek Weir, Bumbuggan Weir, Lake Cargelligo Weir and Booligal Weir.
As part of the dam safety upgrade program,SWC is also required to provide fish passage to offset the modifications Wyangala Dam.
Comprehensive and up-to-date summaries and definitions, conceptual layout diagrams, photos, location maps, monitoring outcomes, and case studies on the points of discussion associated with ‘barriers to fish passage’ and ‘fishways’ can be found at the DPI Fisheries NSW Barrier to Fish Passage and Fishway website pages. NSW Fisheries (2003) have also published a ‘Why do fish need to cross the road?’ booklet which contains practical guidelines forthose involved in the planning, design, construction and maintenance of waterway crossings Australia-wide.