Despite massive efforts to remove it, an invasive starfish has returned to protected waters off south-east Victoria.

The “highly voracious” Northern Pacific seastar has been rediscovered in Wilsons Promontory National Park.

Mark Rodrigue from Parks Victoria says it is a major concern.

“These things are predatory, they live on the bottom of the sea,” he told ABC reporters.

“They feed on quite a range of different species, including some of the animals that humans tend to value highly, things like fish.

“You've got a species that basically interferes with some of the natural cycles of the food chains that should be there.

“We're very concerned that if you get a second population of these animals in other parts of Victoria they provide a stepping stone for invasion of further parts of the coastline.”

The seastars were last found at Tidal River in 2012, leading Parks Victoria divers to launch a project that saw them remove the seastars by hand.

The Northern Pacific seastar’s native waters are in the northern Pacific Ocean around Korea, Japan and eastern China, but with similar conditions found in Victorian coastal areas, they have found a new home.

The experts say the probably arrived in ballast water carried by ships.

“It's a major problem worldwide, not only for seastars but for a whole range of other species that are now unfortunately in Port Philip Bay,” Mr Rodrigue said.

He says people on boats needed to be aware of spreading the seastar's larvae.

The experts urge people to wash their gear with fresh water and ensure it dries on land.

“This is going to be an ongoing problem and I think the important thing for all of us who use boats or who use the marine environment to understand that while these are very prolific breeders, it's humans that can actually play an important role in spreading of these things,” he said.

Parks Victoria is surveying Tidal River to determine how many seastars have infested the area.