Assessment of environmental flows in the Snowy River (fish component)
The amount of water extracted by the Snowy Mountains Scheme is currently only 1% of the natural flow volume. In line with interstate agreements on water reform for the Snowy system, it has been proposed that flows in the river should be increased to as much as 28% of the natural flow volume. This project will provide an assessment of the ecological benefits of environmental flows in the Snowy River. The rationale for the study is that an increase in flow would be beneficial to populations of native fish, such as eels, river blackfish, galaxiids, congolli and smelt.
Fish communities are sampled by electrofishing in six river reaches in the Snowy River, and two reaches in each of four reference rivers in New South Wales and Victoria. Each site is sampled once annually during summer, using electrofishing shots. Fish are identified, counted and measured, and inspected for disease before being returned to the water alive. Detailed habitat assessments are completed with each electrofishing shot to assess changes in habitats as well as fish communities in relation to river flows.
Fish populations were sampled in 3 consecutive years (2000-2002) prior to changes in the flow regime and will be resampled for at least a further 3 years following the implementation of increased river flows in 2003.
1. Establish the condition of the structure and composition of fish communities in the Snowy River before the implementation of environmental flows.
2. Determine whether increased flow will result in greater abundance of native fish, and strengthened population structure through the addition of age classes.
3. Measure habitat diversity and availability for trout species, especially upstream of Snowy Falls, potentially resulting in an increased trout population due to increased flows.
4. Determine levels of interaction between trout and native species with respect to increased flows.
5. Determine whether increased flow will result in a reduction in populations of goldfish and redfin perch.
- Industry & Investment NSW (formerly Department of Primary Industries)
- NSW Office of Water
Dr Dean Gilligan