The Times reported on January 21 that Marmion Lake was being choked by pest weed Salvinia and was also home to a species of feral catfish.
Now the City of Melville says the problem may have originated when just a few fish and a small amount of Salvinia were dumped into the lake.
In a bid to protect native species, the City of Melville is urging the community to avoid dumping plants or animals into local lakes and waterways, and to look out for poachers removing protected flora or fauna from reserves and parklands.
Melville Mayor Russell Aubrey said when non-native species were introduced into lakes and waterways, they would often outcompete native fish, spreading disease and stirring up mud, which ruined vegetation and damaged sensitive waterways.
‘Feral species breed rapidly and can easily take over a water body, decreasing the habitat for our native species and potentially even spreading into the wider river system, which is of great concern,’ he said.
‘Concerningly, the catfish are thought to have originated from just a few being dumped. They quickly overtook the lake in their thousands, leaving no room for the native fish.
‘The Salvinia, which is a common plant used in aquariums, multiplied to cover the entire lake surface, blocking out light, removing oxygen in the water and creating conditions similar to an algal bloom.’
Mr Aubrey said the City tried a number of treatments, but were left with no choice but to drain the lake, remove the catfish manually, transfer native wildlife such as turtles to an alternative location and treat the remaining water in the lake.
The lake has now been refilled with water and will soon be stocked with native fish.
‘Something else I would also ask residents to keep a look out for at their local parks and lakes are poachers,’ he said. ‘Sadly, poachers are stealing our native animals either for consumption, to keep as pets or to sell and import illegally to overseas clients.’
The law of the lake
– It is illegal to remove any flora or fauna from reserves, parklands or their
– Heavy penalties apply for convictions.
– Report suspicious behaviour to Wildcare helpline 9474 9055.
– Anything unusual in waterways can be reported to FishWatch 1800 815
– The RSPCA can assist with the humane disposal of unwanted or diseased
– Report all poaching, rescue and dumping incidents to the City of Melville
environmental officer on 9364 0283 or
– Visit www.melvillecity.com.au/wildlifeissues for more information about