After a community volunteer group cleared an astounding 260 kilograms of one of Australia’s most invasive species from waterways in the country’s south, an industry specialist is calling on others to step up and support the effort.
While it might be near-impossible to remove the North Pacific seastar from Australian waters altogether — with tens of millions of the introduced marine pest in Tasmania alone — every effort can make a difference, the Invasive Species Council’s Dr Tiana Pirtle told Yahoo News Australia.
It comes after the Invasive Seastar Clean Up group removed mountains of seastars from the ocean earlier this week during their 64th event. Benita Vincent lives in the state and runs the program. Speaking to Yahoo, Vincent explained how she, alongside other dedicated volunteers, have removed more than 200,000 seastars from local waters, particularly around the Derwent River.
The toxic species thrives in plague proportions in southern Australia, after arriving in the country as stowaways on ships in the 1980s.
Recent estimates suggest there are as many as 30 million in Tasmanian waters, where the species significantly impacts local ecosystems by preying on native shellfish, including commercially important species such as scallops and oysters.
The Invasive Seastar Clean Up group has now held an incredible 64 events in Tasmania. Source: Facebook/Keith Thomas-Wurth
Why are sea stars so invasive?
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.
While it might be effectively impossible to eliminate them altogether, we can help to protect local ecosystems from introduced threats, Pirtle argued.
“This is a big issue for invasive species management,” she told Yahoo. “When you have open contiguous landscapes — like the entire ocean — it is near impossible to eradicate some species, even terrestrial animals in Australia, we will probably never eradicate feral cats from mainland Australia.
“We just don’t have the tools. You can control populations at a local scale in these open landscapes, but you’re always going to keep getting more individuals coming in, and that’s the same with the seastars.
“Controlling at a local level can definitely protect local environmental assets, but you’re going to keep getting individuals migrating in. As soon as you remove a bunch of individuals, it creates a vacuum, and now there’s more resources available, and it’s quite attractive for new individuals to come in.
“Unfortunately, I think we are fighting a losing battle sometimes on that regard. But that’s not to say local control programs can make a difference at a very local scale.”
Making the matter even more complicated is the fact seastars “breed so fast and so voraciously”, Vincent added. “They release thousands of eggs per individual, so it’s hard to imagine how many they would produce each year — but it’s billions,” she earlier 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.”
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