30-06-2025
Grim underwater find prompts calls to make $43.9 million change in Aussie waters
Sea urchins are being found in alarming numbers in waters surrounding one of Australia's largest cities, but researchers believe culling them could create $92 million in benefits. A team from RMIT believe multiple industries could benefit if Port Phillip Bay's kelp forests they're destroying, are allowed to recover.
Sea urchins are native to waters around Melbourne and feed on kelp, but warming waters and changing ocean currents have caused their numbers to reach 'unsustainable population levels', and pictures taken by RMIT divers show things are looking grim in many parts of the ocean. Kelp coverage in the greater region has declined by up to 98 per cent in the region over the last 40 years.
Because the changing ocean conditions that favour the urchins are caused by climate change, their numbers aren't expected to naturally correct themselves, which is why the researchers argue intervention is needed. The study found that reducing urchin numbers and allowing the kelp forests to recover would reduce nitrogen and phosphorus in the water.
Carrying out the plan would be expensive, with an investment of $43.9 million needed to create $92.1 million in benefits.
But the study's lead author, Dr Paul Carnell, argues the plan would be a 'smart economic investment' for government. 'This approach can be targeted to specific areas of the bay, so we can get the greatest bang for our buck,' he said.
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The plan could see the tourism sector profit as kelp forests are a drawcard for divers and snorkellers. Fish stocks would also likely improve, aiding both commercial and recreational fishers. But the biggest beneficiary would likely be the wider environment, as kept forests play an important role in water purification and carbon sequestering, a major cause of global warming.
In Victoria, the collection of urchins is regulated, and there is a bag limit of 40. While they're in problematic numbers, they are actually a valuable resource and considered a delicacy in some Asian cultures. In Australia, some premium urchin roe can retail for almost $700 for 120 grams, but there are cheaper alternatives for as little as $60 per 100 grams.
The study has been published in the journal published in Ecosystem Services.
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