The turtle, native to North America, grows to between 12.5 and 28 centimetres and has been named in the top 100 most invasive alien species by the International Union for Conservation of Nature.
Baigup Wetlands Interest Group co-ordinator Penny Lee said members from the group had sighted the turtle on four occasions and were concerned by the lack of action taken by the Department of Agriculture and Food.
The wetland is located along the Swan River below Stone Street on the Maylands and Bayswater border.
Get in front of tomorrow's news for FREE
Journalism for the curious Australian across politics, business, culture and opinion.
READ NOW‘I’m surprised if they think it’s such a major potential hazard, as far as we know there are no colonies in WA, why wouldn’t you attend to it?,’ she said.
‘Is it or is it not a serious threat, if it is a serious threat, why aren’t they doing something about it?’
Ms Lee said the turtle puts stress on any ecosystem that is already heavily under strain from other introduced species.
‘Nowadays you’ve got cats, you’ve got foxes, you’ve got introduced rats, as well as the native water rats, and now you’ve got an introduced turtle.
‘Now one turtle is probably not a disaster but if it were to breed and form a colony it would be, you have just simply thrown the whole ecology out of balance.
Ms Lee said she thought the fines for having a red-eared slider turtle were so harsh that it might be discouraging people from handing in the pets in a proper way, rather choosing to leave them in lakes and rivers to avoid the fine.
‘If you’re dealing with a pet shop or dealer, by all means hit them with maximum full fine.
‘But if you’re dealing with a private individual who might or might not have bought the pet, there’s no point in threatening them with a huge fine.
‘They obviously have to be enticed to do the right thing with the animal.’