Dr Beatty says it is almost impossible to completely eradicate a freshwater fish species once it has been introduced. Image: DonnikowskiTHE Department of Fisheries WA intends to increase its public awareness program to reduce the number of ornamental fish species being introduced into WA’s rivers and wetland systems by engaging members of the public.
In participating pet shops, clear plastic bags supplied for customers to take live fish home are to be labelled with a message warning against the dangers of “dumping” fish into rivers and wetlands.
The program, which is set to be trialled in coming months, comes after the recent capture of enormous goldfish (Carassius auratus auratus), pearl cichlid (Geophagus brasiliensis) and other invasive fish species in WA waters.
Mr Bruce Mackay, aquatic biosecurity officer of the Department of Fisheries, says members of the public who free their fish are causing major problems for native fish species.
“The general public should never, ever release their fish into the natural environment,” he says.
“Thirty-four exotic freshwater fish species are known to be established in Australian waterways.
“Twenty-two of those species are believed to have originated from the ornamental fish industry.”
Dr Stephen Beatty from Murdoch University’s Freshwater Fish Group and Fish Health Unit says the number of freshwater fish introduced into WA waters has increased by about 60 per cent in the last 40 years.
“In the South West region of WA there are 13 introduced freshwater fish species in the natural environment,” he says.
“That is more than the total number of native species, which is 11.”
Dr Beatty says it is almost impossible to completely eradicate a freshwater fish species once it has been introduced.
“Rivers can be quite large and they are connected to each other, so short of draining or poisoning a system completely, eradication is often not feasible,” he says.
Introduced species can have catastrophic impacts on native species, most of which are smaller in size, by causing regime shifts, increasing competition for food, and disturbing the environment.
Dr Beatty says most people who release fish into water systems are unaware of the risks, thus the need to raise public awareness.
“Our theory is that well-meaning people who do not want to kill their pets innocently release them when they move house,” he says.
“Another reason is the introduction of fish for recreational fishing but we do not advocate this at all.
“With education and better understanding of the impact, people will think twice about dumping fish into rivers.”
The Department of Fisheries is also trialling traps to target the common carp and goldfish without catching native species.
