This document aims to minimise impacts on fish passage and general aquatic wildlife by providing practical guidelines to those involved in the planning, design, construction and maintenance of waterway crossings. Considerable effort has been taken to make these guidelines applicable across Australia; however, local knowledge, data and experience should always be used to enhance, modify or even replace the information presented within these guidelines. Your local fisheries department/authority can provide additional information on fish species, design or approval requirements relevant to your area.
WHY IS FISH PASSAGE IMPORTANT?
Fish passage along our waterways is critical to the survival of Australian native fish. Species of both fresh and saltwater fish move within waters at different times to access food and shelter, to avoid predators, and to seek out mates to breed and reproduce.
Examples of the various types and reasons for fish movement include:
Local movement ➔ access food, avoid predators, shelter during daylight.
Daily movement ➔ access habitat, food and shelter, defend territory, avoid predators.
Seasonal movement ➔ breeding cycle in response to rising water levels or temperatures.
Upstream movement ➔ access to new habitats or established spawning areas.
Downstream movement ➔ post-spawning movement, avoid predators.
Lateral movement ➔ access food, breeding cycle and juvenile recruitment to habitat areas.
Of the 83 species of freshwater fish in southeastern Australia, half migrate at least once as part of their life cycle. Four notable long distance swimmers are the Mary River cod (30km), silver perch (570km), Murray cod (1,000 km) and the golden perch which has been recorded swimming a staggering 2,300km.
Approximately 70 per cent of the coastal species in south- eastern Australia also migrate to complete their lifecycles. The sea mullet, a popular commercially caught fish, enters freshwater habitats as a juvenile, then migrates into estuary waters in preparation for annual spawning. Australian bass and barramundi, both prized recreational fish species, migrate from freshwater to estuaries to spawn, and the juveniles then migrate back upstream.
Species such as the climbing galaxias, mangrove jack and flat-tail mullet move up and down rivers or to and from the ocean just to search for food or to avoid predators.
The numbers of fish undertaking movement at any one time can also be staggering. For example, 6000 juvenile fish were recorded in one day moving upstream through a fishway on the Mary River in south-eastern Queensland.
fish passage requirements for waterways crossings