Fish Passage in NSW

Aboriginal people have deep connection to native fish and the rivers. Traditional Custodians are the first natural resource managers. For thousands of years they have curated a landscape where water is the thread that weaves Country together, cascading into the rivers that bring life all across the landscape. They have created a landscape that is sustainable and productive, and understood that where native fish can move within their natural migratory patterns, all of Country, including people, thrive.

Over 100 years ago the (then) NSW Department of Fisheries recognised the importance of fish migration and the potential for instream structures to impact on the health of fish populations. Since then our knowledge of the native fish fauna has grown and we have witnessed the negative impact of poorly designed weirs, road crossings, and floodgates on fish populations, and have realised that their effect is far greater than first thought.

The NSW Department of Primary Industries and Regional Development Fisheries and Forestry (DPIRD Fisheries) acts to ensure the free passage of fish within NSW waterways.

The importance of connectivity

Stream connectivity and habitat diversity are critical components of healthy waterways, with many native fish evolving to be reliant on a variety of different habitat types throughout their life. The free passage of fish within rivers and streams, and between estuarine and freshwater environments is a critical aspect of aquatic ecology.

For example, researchers have observed tagged Golden Perch migrating thousands of kilometres across Australia's largest river system, the Murray Darling Basin¹. More recently they have used water chemistry to investigate Golden Perch and Murray Cod population dynamics². By analysing chemical tracers in fish ear bones, they have found that Golden Perch sub-populations interact with those in other Basin rivers. This is despite fish being separated by hundreds or thousands of kilometres. Movement of fish from other regions was identified as a strong driver of population dynamics in some regions.

Connectivity, especially between tributary and mainstem habitats can be a substantial driver of population structure for both Golden Perch and Murray Cod. Ensuring there is connectivity between tributary and mainstem environments is therefore important to ensure healthy fish populations. The map below shows fishway locations across NSW. These fishways help connect river reaches and provide fish passage.

But it isn't only the fish who benefit from improving structures to provide fish passage. By replacing low lying road crossings, such as causeways or pipe culverts with box culverts and bridges, safer crossing points for people and vehicles are created. This in turn reduces the burden on emergency services during high or flooding flows as they no longer need to perform flood rescues at those sites.

References:

^{1.  Reynolds L.F. (1983) Migration patterns of five fish species in the Murray-Darling River system. Marine and Freshwater Research 34: 857-871.}

^{2. Price A., Balcombe S., Humphries P., King A., Zampatti B. (2019) Murray‒Darling Basin Environmental Water Knowledge and Research Project — Fish Theme Research Report. Report prepared for the Department of the Environment and Energy, Commonwealth Environmental Water Office by La Trobe University, Centre for Freshwater, CFE Publication 223 June 2019 41p. [Appendices 203p.]}

NSW fishways