Aquatic Plants and Animals
The freshwater environment of the Namoi Catchment is comprised of an extensive range of aquatic habitats including swamps, floodplains, wetlands, streams and rivers. Within these broad habitat types, niche habitats such as pools and riffles, gravel beds, snags, aquatic vegetation and riparian vegetation are present, diversifying the habitat available to aquatic species.
This extensive range of aquatic habitat supports a diverse assembly of species, including over 20 freshwater finfish species. Six of these species are introduced, competing with 16 native fish species found within the catchment. The pressures from introduced species, as well as other factors such as increased fishing pressure and habitat degradation, have resulted in the population densities of native fish being significantly lower than historical levels.
Aquatic species are dependent on healthy waterways and access to a range of diverse habitats for their survival. Aquatic habitats can be degraded by poor water quality including thermal pollution and oxygen depleted water from dam releases, degraded aquatic and bank vegetation along with in stream barriers to fish passage.
The report called The Assessment & Modification of Barriers to Fish Passage in the Namoi Catchment is on the Namoi CMA website under publications. This report identifies the significant barriers to fish passage across the catchment.
Low levels of remaining native vegetation have resulted in unstable stream banks and bed lowering, especially in the middle and lower catchment. On average, there is only 30% tree cover within the riparian zone across the catchment. The worst cover occurs in the Goonoo Goonoo subcatchment. Poor vegetation results in minimal shade and protection and also leads to sedimentation and nutrients in surface water which threaten aquatic biota.