 Since the construction of the Canning Dam , among other drinking water supply dams , water flow into the Canning River has been reduced by up to 96 % . A number of freshwater fish species which are endemic to the south @-@ west of Western Australia are found in the Canning River system , however studies of fish and fish habitats in the area have shown that fish numbers are low due to a loss of habitat and a loss of <unk> between breeding areas due to low flows , preventing fish migrating upstream and reaching important breeding and nursery grounds . <unk> water caused by a lack of water flow has provided a suitable habitat for successful breeding of an introduced pest , the <unk> . 
