The main threat to the health, abundance and diversity of fish in NSW is the destruction of their habitat.
Many fish need to travel a long way to survive, escape predators and competitors, and breed and rear in different waters. Many are stopped from migrating by barriers, such as dams, weirs, floodgates and road crossings.
Human activities that destroy aquatic vegetation, block channels and waterways, and disturb the balance between sediment and water flows in rivers and estuaries all contribute to the destruction of fish habitat.
Removing native trees and plants, especially along creek and river banks, means less habitat and food for fish. Clearing also increases sediment and nutrient supply into the water.
Bank erosion on the Peel River, Tamworth. Photo: Sharon Molloy
Weirs, floodgates, and poorly designed road crossings can prevent fish from moving upstream and downstream for feeding, shelter, and spawning.
Boomi Weir - an example of a barrier that prevents fish from migrating. Photo: C. Jenkins
Drained wetlands result in the loss of valuable nursery grounds for fish.Over-drainage can increase the exposure of acid sulfate soils and contribute to the discharge of poor quality water into our rivers and estuaries.
Uncontrolled stock access can cause bank erosion and increase the nutrient input into our waterways resulting in algal blooms and sedimentation.
Cattle on Ryans Island, grazing the banks of the Buckenbowra River. Photo: Trevor Daly
Snags provide shelter, protection and spawning sites for a range of native species.
This creek still has snags available for fish to use. Photo: C. Jenkins