Eight platypuses have been found dead long before they were trapped in an illegal yabby network.
Three teenage girls were kayaking on the Werribee River, west of Melbourne, on Saturday morning, when they closed the bait trap and made the grim discovery.
This has been the worst incident of platypus killed since 2016, when four bodies were found in another river in Melbourne.
The incident was reported immediately to the Werribee River Association.
Eight dead platypus found dead by three teenagers kayaking down a river in Melbourne.
"The amount of dead platypus found has been amazing," Weribee Riverkeepr John Forrester told Daily Mail Australia.
Forrester suspects that the opera bait nets had been planted in the river to trap yabbies, one of the favorites of the native platypus.
The Department of Environment, Lands, Water and Planning is carrying out an investigation into the network where the platypus were captured.
The government department of Victoria will analyze how the bait trap was made, where it was sold, and determine the weight, sex, and amount of time that the platypus were trapped underwater.
Forrester suspects that one or two corpses had been in the water for a few days, as some of them had lost some hair and had visible white flesh.
The government of the state of Victoria will make the transition to a total ban on river networks beginning in July of next year. Fishermen should opt for friendly versions for wildlife.
The last report of dead platypus found in a Melbourne river was two years ago.
"Of course they can drown, they can last up to two minutes, like a human being in the water, out of breath," he told ABC News.
"This has been the biggest and most distressing case," said Mr. Forrester.
Forrester suspects that the opera bait nets had been planted in the river to trap yabbies.