Fish-monitoring program within the Eastern Mount Lofty Ranges
MDFRC Technical Report No. 7/2003
The Eastern Mount Lofty Ranges (EMLR) is a series of catchments at the terminus of the River Murray. The area has a diverse array of geomorphological and hydrological variability that supports significant yet fragile native fish communities. Recent fish surveys have revealed widespread reductions in range and abundance of native fish within the EMLR and this has been attributed to several factors including: reduced flows, stock grazing, land clearing, and the introduction of alien fish species. This report is part of a River Murray Catchment Water Management Board program monitoring the status of significant fish communities in relation to environmental variability at sites within the Eastern Mount Lofty Ranges (EMLR). Twenty-four sites were surveyed by the Murray Darling Freshwater Research Centre and ‘Aquasave’ during April 2003 in stream and wetland environments associated with the Angas River, Finniss River, Tookayerta Creek and Marne River catchments, as well as two drain sites on the edge of Lake Alexandrina in April 2003. The significant fish communities and habitat characteristics surveyed at sites within the EMLR varied substantially between catchments and sites within catchments but were generally consistent with previous surveys in 2001 and 2002. Drought conditions leading up to the 2003 study was thought to have contributed to the increase in electrical conductivity at sites within the Marne River catchment and substantially reduced the maximum depth at a site in the Tookayerta Creek. Anthropogenic disturbance was apparent at several sites in the Finniss River Catchment, a site on Lake Alexandrina and at one site in the Marne River Catchment. Significant fish species such as southern pygmy perch (Nannoperca australis), river blackfish (Gadopsis marmoratus) and mountain galaxias (Galaxias olidus) were collected from new sites in the Angas River, Tookayerta Creek and Marne River catchments but generally occurred in low abundance and were restricted to a limited number of sites within the EMLR. Dwarf flatheaded gudgeons (Philypnodon sp.), southern pygmy perch and mountain galaxias were absent from a few sites within the EMLR catchments compared to previous surveys. Alien species occurred at few of the sites sampled and were generally sampled in low abundance. However the presence of large predatory species such as redfin (Perca fluviatilis) and brown trout (Salmo trutta) may have contributed to our failure to collect mountain galaxias at a site in the Angas River and habitat partitioning in a pool at a site in the Finniss River. Due to the restricted range and low abundance of many of the significant fish species within the EMLR, continued monitoring of fish communities and habitat characteristics is recommended.
MDFRC funding agency: River Murray Catchment Water Management Board
MDFRC client: River Murray Catchment Water Management Board (South Australia Murray-Darling Basin Natural Resources Management Board)