Reports of a significant die-off of the Northern Pacific seastar, a highly invasive marine pest, have been confirmed at Carrum on Port Phillip Bay.
Agriculture Victoria Principal Officer Invasive Marine Species, Dr Richard Stafford-Bell, said the Northern Pacific seastar was first detected in Port Phillip Bay in 1995, and by 2000 a significant population of the seastar had established.
“There has been sporadic die-off of the seastar in the Carrum area since the middle of last year and this recent report indicates a significant die-off with about 1,000 Northern Pacific seastars washing ashore,” Dr Stafford-Bell said.
“It is a widespread and well-established marine pest in Port Phillip Bay and cannot be eradicated. There have been large numbers of dead seastars reported from around the bay at various times, including under nearby Mornington Pier, where many thousands were seen by divers in 2010, and more recently in the Maribyrnong River.”
Dr Stafford-Bell said that following rapid increases in numbers, competition between individuals for remaining food can lead to significant numbers of seastars dying and washing up on shore.
The key features of the Northern Pacific seastar are its five-pointed arms with upturned tips and yellow and purple markings.
The species is an opportunistic predator that consumes a large variety of prey. In high densities, it can have severe effects on wild and cultured shellfish populations, and on native biodiversity.
Bay users should be aware that marine pests can spread easily to new areas of Victoria through movement of recreational equipment such as boats, kayaks and canoes, and fishing equipment.
Dr Stafford-Bell urged people using marine equipment in the affected area to wash equipment in fresh water after use and then thoroughly dry it to reduce the risk of spreading marine pests to other marine areas.
“This is particularly important for people moving any equipment used in Port Phillip Bay to other areas,” he said.
He added that Northern Pacific seastars are not poisonous or dangerous to people or domestic animals, and asked that beachgoers finding Northern Pacific seastars washed up on the shoreline, not to return them to the water.
