Murdoch University scientists have found the state’s South-West unique freshwater fish populations are reducing, with a number being listed as endangered.
According to Murdoch University’s freshwater fish experts Drs David Morgan and Stephen Beatty the combination of habitat change, decline in water quality and introduction of exotic fishes has had a major impact.
The pair recently spoke at the International Union for Conservation of Nature (IUCN)workshop in Adelaide, revealing the results of their extensive surveys in every river system in South-Western Australia.
“Eighty percent of our South-West species are only found here and play an important role in structuring aquatic ecosystems,” said Dr Morgan, Murdoch’s Centre for Fish and Fisheries Research freshwater fish expert.
“The combination of habitat change, decline in water quality and introduction of exotic fishes has had a major impact on the distribution species and led to a number being listed as endangered.
“The other concern is recent work has shown genetic differences between populations so losing them results in the loss of important genetic information.”
The research team surveyed over 2000 sites in the South-West of Western Australia.
Dr Beatty, also from the Centre for Fish and Fisheries Research, said their findings had also shown fresh groundwater intrusions, such as spring-fed tributaries, were crucial in allowing remnant fish populations to exist.
“These areas of fresh groundwater intrusions in systems such as the Blackwood River effectively dilute the main channel and maintain permanent tributary habitats for threatened species such as the Balston’s Pygmy Perch,” he said.
“Therefore it is very important to maintain this input – particularly in light of the predicted reduction in rainfall due to climatic change in the South-West.
“The surveys have mapped the introduction and colonisation of feral fishes such as Goldfish and Mosquitofish that are also having a massive impact on these fishes.
“In fact, our research has shown that there are now more species of exotic fishes than natives in these waterways, with a number of new species having being recently recorded.”
The IUCN workshop reached a major consensus that a greater level of collaboration was needed between scientists, aquatic managers and the wider community to ensure the effective use of resources in conserving the unique fish fauna of Australia.
Image: Courtesy of David Morgan, Centre for Fish and Fisheries Research, a Nannatherina balstoni from the South-West.