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Ecological assessment of Denmark Dam and potential relocation pools for aquatic fauna in the Denmark River. Report to the Water Corporation of Western Australia

Ryan, T., Beatty, S., Keleher, J., Allen, M. and Morgan, D. (2015) Ecological assessment of Denmark Dam and potential relocation pools for aquatic fauna in the Denmark River. Report to the Water Corporation of Western Australia. Freshwater Fish Group & Fish Health Unit, Centre for Fish & Fisheries Research, Murdoch University, Perth, Western Australia.

Abstract

The current report outlines the results of an ecological survey conducted between February and April 2015 in the Denmark Dam and the Denmark River. The lowering of the water level in Denmark Dam is scheduled to occur between December 2015 and April 2016, and is planned to be a drop from full supply level of 20.7 mAHD (450 ML), initially to 18 m AHD (~100 ML) and then to the required lower range of between 16.5 mAHD (~33 ML) and 14.3 mAHD (~4 ML). Given the large reduction in water volume and aquatic habitat, an assessment of the potential ecological impacts on the resident aquatic fauna was necessary. An initial survey (see Beatty et al. 2014) conducted in June 2014 revealed that there were substantial populations of native freshwater fishes in the reservoir, as well as a viable (but relatively small) population of Smooth Marron in the reservoir. It was recommended that an investigation be made into locating potential sites (i.e. refuge pools in the Denmark River) for the relocation of this fauna during the draining of the reservoir. This would mitigate the potential for large mortalities of the aquatic fauna in the remnant water body that could arise through either poor water quality or increased competition and predation. The latter study also recommended that the reservoir be re‐surveyed at a time that better matched the planned draindown period to provide additional and more comparable data on the abundances of the different aquatic fauna that is most likely to be encountered at the time of draining.

Publication Type: Report
Murdoch Affiliation: School of Veterinary and Life Sciences
Centre for Fish and Fisheries Research
Freshwater Fish Group & Fish Health Unit
Publisher: Freshwater Fish Group & Fish Health Unit, Centre for Fish & Fisheries Research, Murdoch University
URI: http://researchrepository.murdoch.edu.au/id/eprint/36482
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