Seven platypus dead in net in Vic river

An net illegal set up on Melbourne's Werribee River has killed seven platypuses, out of a local population of less than 50.

Seven platypuses have been found dead in an illegally set net in a Melbourne river.

The environment department announced on Monday it was investigating the death of the mammals - found at varying decomposition stages - in the Werribee River which has a platypus population of less than 50.

"This is devastating news and we are shocked that one net in one week can make such an impact on an iconic animal," department wildlife officer Abby Smith said of the deaths discovered on Sunday.

"We don't think the person responsible intended to catch platypus, but the destruction it has caused shows a complete lack of understanding a net like this can cause."