Bizarrely, the knife believed to have been used in the attack on the sign, along with a name and phone number, were left at the scene.

Both are now being investigated by police.

The billboard was erected by Australian Wildlife Society and Regional Victorians Opposed to Duck Shooting at Rosedale, in Gippsland.

Rosedale itself is not a noted duck shooting area but "it is on the road" to some popular wetlands, according to a spokeswoman for Regional Victorians Opposed to Duck Shooting, Kerrie Allen.

Ms Allen said the billboard was cut up early last week and would be replaced in the next few days.

"This time it is going to have security cameras on it."

Ms Allen agreed it was not known whether a hunter was responsible for the damage.

"There has been a lot of comments on social media from hunters supporting the action though," she said.

Each year there is a struggle between shooters and those opposed to duck hunting as the Victorian government considers whether to allow a duck hunting season or not.

The season generally opens in mid-March after surveys of duck numbers and consideration over the state of the many wetlands.

Duck hunting is also a welcome contributor to the economy of many regional towns.