PORTLAND’S botanical heritage is under threat from an overpopulation of possums, which council workers say are being illegally released into the Portland Botanic Gardens.

Several of the original trees planted in the 180-year-old gardens are under significant stress from the marsupials stripping leaves off them, while many other plants are also affected.

Recently, Glenelg Shire Council’s parks and gardens staff have witnessed people freeing trapped possums into the area, something gardens team leader Bill Buck suspects has been going on for a while.

“It’s heartbreaking for the staff to see it happening,” Mr Buck said.

“The damage really is quite significant, they’re important, old trees in Victoria’s third oldest garden, and we’re concerned that some might not recover.”

“They moved on to the roses as well, and when we sowed a crop of green manure from the dahlias the whole bed got completely eaten.”

The parks and gardens team look after the whole shire area (which includes the mammoth three-month job of pruning roses) but have been hard at work in Portland putting in barriers and tree guards to try and keep the possums at bay.

The park has always had a native resident population of both ringtail and brushtail possums, but Mr Buck said their regular population survey have shown a boom in numbers.

Because the park is a cut off ‘island’ of trees with good food and shelter available, the introduced possums do not move on to other areas, so the pressure on the plants intensifies as the population grows.

Mr Buck said some of the large specimens of slow growing species like one of the Gingko trees are irreplaceable, and asked the public to stop causing potentially inadvertent harm.

“It is just compounding what’s actually a really serious problem for us here,” he said.

“I think most people who are doing this, releasing possums, probably think they’re doing the right thing by letting them go here, they think it’s a nice place for a possum to live.

“Well, it is, maybe too nice because they are all staying and doing this damage.”

Mr Buck sad they are trying to avoid using other methods of population management, but that is not easy with possums being left at their doorstep.

Trapping a brushtail possum is allowed in Victoria, but they need to be released on the same property that they are caught at – typically this is to get them out of a roof or building.

It is illegal to trap a brushtail without a permit.

Possums must be released within 50m of the trap, after sunset on the same day they are caught, where it is not reasonably possible to release the possum on your property, possums must be humanely destroyed by a registered vet within 24 hours of capture.

There are further regulations on the type o trap and how they are used.

According to the Department of Energy, Environment and Climate Action (DEECA), there are no other legal avenues to deal with possums, which are protected under the Wildlife Act 1975.

Breaches of the above requirements can carry a penalty of up to $9246 under the Wildlife Act 1975 and/or 2 years imprisonment or $44,380 under the Prevention of Cruelty to Animals Regulation 2016.