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Devastating change taking place at Australia's 'best beach': '20 million of them'
It was voted as Australia's Best Beach a few short months ago, but under the surface a dark shift is taking place. An army of invaders is turning the sea bed into a barren wasteland, and experts fear the threat could destroy up to 50 per cent of reefs along the state's coastline if more isn't done to stop it.
In February, a stretch of beaches along the famed Bay of Fires on Tasmania's east coast was awarded the title of the best beach in the country. But Dr John Keane, a fisheries research fellow at the Institute for Marine and Antarctic Studies, says underneath the surface it's a different story.
Longspined sea urchins, also known as centro from their scientific name centrostephanus rodgersii, have arrived in Tasmania's oceans in droves. Dr Keane estimates the population has grown to more than 20 million.
"What makes them so damaging is they've got a very broad spectrum of diet," he said.
As well as targeting lush kelp forests, they also eat sessile invertebrates like sponges, corals, anemones and sea squirts.
"They basically eat anything on the reefscape and they leave that barren rock that can extend for kilometres."
The urchins have been found all the way down the state's east coast, reaching as far south as Port Arthur.
Several climate factors are working together to draw the urchin larvae further south than ever before.
Tasmania's waters are warming at a rate of twice the global average, according to the CSIRO. The East Australian Current is extending further south, pushing warmer water towards Tasmania.
Combined with the general warming of climate change, it's creating a "double effect", Dr Keane said.
This creates an environment suitable for the centro to thrive – and take over.
Dr Keane believes harvesting urchins is a viable solution, as the buttery golden roe is considered a delicacy and can sell for more than $500 per kg.
Up until recently, 500 tonnes of centro were being harvested every year and some sites were seeing a successful decline in numbers alongside the return of kelp.
While it was a win for the environment, it was also a win for the Tasmanian economy.
The fledgling industry has created jobs in multiple areas, injecting revenue into the state and adding a new taste to Tasmania's already impressive spread of local flavours.
Recently, the efforts to manage the urchins have slowed down after the closure of one of the state's major processing facilities.
Dr Keane said the company was harvesting around 400 tonnes of centro annually – about 80 per cent of state's collective total – which has left a hole in the market.
While smaller businesses are trying to fill that void, they don't have the capacity to handle the same volume of urchins.
"There are plenty of divers wanting to go catch these sea urchins. But there's not the market and the processing capacity to be able to do that at the moment," Dr Keane said.
Because the catches have declined, data is now showing evidence of the urchin population growing.
"The other option is to go out there and kill them without processing, which can be done and it's quite effective, but it's highly expensive," he added.
If no control measures were in place, Dr Keane estimates 50 per cent of Tasmania's reefs would barren in 10 years.
He's hopeful that change is coming, and the biggest difference could be made through government support.
"We need funding to support the industry. That's the solution," Dr Keane said.
"Temperate reefs just aren't as sexy as tropical reefs. The Great Southern Reef gets 1 per cent of the funding that the tropical reefs do.
"It just doesn't have that iconic image of snorkelling on a coral reef. All the tropical fish. Even though temperate reefs have some amazing biodiversity and kelps and sponge gardens and it's so beautiful, it just doesn't get the light of day, unfortunately."
Tasmanians will head to the polls in a matter of weeks for the state election, with Dr Keane reminding residents that change begins with a vote.
"If we don't get this fishery up and running, we're just going to continue to lose more reefs, and then that all negatively impacts other commercial fisheries such as rock lobster and abalone, it'll impact tourism, and impact biodiversity and the environment more generally."
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