A decline in the trout fishery, water quality and ecological values of lakes Sorell and Crescent has occurred over the past few years. In light of these problems, the Inland Fisheries Service (IFS) secured State and Commonwealth (Natural Heritage Trust) funding to implement on-ground works and formulate management options to address the recent environmental decline. The key problem associated with the lakes is low water levels due primarily to drought conditions and competition for water by various users. A multi-disciplinary project was adopted to address the situation – the Lakes Sorell and Crescent Rehabilitation Project. This project was comprised of ten sub-projects targeting key areas of physical and biological importance to the functioning and management of lakes Crescent and Sorell. The ten sub-projects were:

• Lake Crescent Outflow Screen Duplication
• Mountain Creek Rehabilitation
• Catchment Management Plan
• Water Management Plan
• Water Quality
• Wetlands
• Aquatic Fauna
• Recreational Fisheries
• Carp Management
• Ecological Modelling

This report outlines some of the findings and management recommendations for the Aquatic Fauna Sub-project.

The aquatic fauna of lakes Crescent and Sorell thought to be of particular importance, in terms of the health of the aquatic eco-systems and conservation value, were populations of the ‘rare’ and endemic freshwater fish, golden galaxias (Galaxias auratus), and the macroinvertebrate communities of both lakes. It was suspected prior to the project that the recent decline in the environmental condition of lakes Crescent and Sorell had adversely impacted on these faunal components of the lakes.

The Aquatic Fauna Sub-project of the Lakes Sorell and Crescent Rehabilitation Project involved studying the ecology and current status of populations of G. auratus and also the current status of macroinvertebrate communities in lakes Crescent and Sorell. The project also focused on defining the threatening processes which these fauna are facing.

This report, ‘‘Current Status of the Macroinvertebrate Communities in Lakes Crescent and Sorell’, documents the results of the work that was undertaken on the invertebrate communities during the Aquatic Fauna Sub-project and details recommendations for the future management of lakes Crescent and Sorell. The results of the G. auratus study are documented in a separate report (Hardie 2003).