Environmental advocates are summoning the public to come forward and assist with efforts to help remove the highly invasive Northern Pacific seastar from waters around the country’s south.
The toxic species thrives in plague proportions in southern Australia, largely in Tasmania but in parts of Victoria too, after arriving in Australia as stowaways on ships in the 1980s.
Recent estimates suggest there are as many as 30 million seastars in Tasmanian waters alone, where the species significantly impacts local ecosystems by preying on native shellfish, including commercially important species such as scallops and oysters.
Like many introduced threats, the Northern Pacific seastar has no natural predators in Australia — though they do north of the equator — meaning they’re able to breed prolifically, almost totally unchallenged by any competitor.
Benita Vincent lives in the state and runs the recurring Invasive Seastar Clean Up, now approaching its 64th event. Speaking to Yahoo News Australia, Vincent said she, alongside other dedicated volunteers, have removed approximately 200,000 seastars from local waters, particularly around the Derwent River.
That equates to roughly 9,500 kilograms worth of organisms, collected across dozens of clean-ups.
A permit is required to remove seastars from Tasmanian waterways, due to the fact they can be easily confused with natives. Source: Facebook/Keith Thomas-Wurth
Removing invasive seastars ‘near impossible’ but every bit counts
Vincent said removing the Northern Pacific seastar altogether from Australia is near-impossible due the fact they “breed so fast and so voraciously”. “They release thousands of eggs per individual, so it’s hard to imagine how many they would produce each year — but it’s billions,” Vincent told Yahoo News.
“We’re talking about the ocean here. It’s impossible to capture something in the ocean on that scale, they just breed like crazy and there’s nothing that bothers them.” Online, volunteers recently shared photos of the incredible volume of seastars they hauled out of the ocean in one trip — “exactly 1,000 seastars at around 40kg”.
According to Tasmania’s Department of Natural Resources and Environment, seastars have been recorded from Banks Strait in the state’s north, to Recherche Bay in the south.
It’s believed the Northern Pacific seastar arrived in Australia in the 1980s on ships and has since exploded in numbers, with some estimates warning there are now 30 million. Source: Tasmanian/Victorian Governments
The highest population densities are found in sheltered bays in southeast Tasmania, particularly the Derwent Estuary. The predator disrupts marine biodiversity and affects the livelihoods of local fisheries, with their ability to tolerate various environmental conditions allowing them to spread quickly.
Vincent said that she believes because “eradication is impossible”, governments will not “invest any money” in those efforts, believing it’d largely be fruitless. This is why she started her event, to help make as much of a dent in local colony numbers as possible, in turn minimising the impact on native species.
“That’s the whole basis of the volunteer program,” she said. “But there’s a permit required for collection, so the best thing to do is get in touch with someone from our page, take a photo, and make sure you know what you’re looking at first.”
It’s important species are properly identified, as Tasmania is home to several native species of seastar, which play important roles in the local ecosystems. These natives differ significantly from invasive species like the Northern Pacific, as they have evolved within the local ecosystem and maintain a balanced relationship with other marine organisms.
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