A vast algal bloom is devasting parts of South Australia's seafood industry.

Straits Times

4 days ago

In South Australia, where the algal bloom remained resident for weeks to months, tonnes of seagrass has washed ashore, mostly out of season.
– In April 2025, Mr Steve Bowley, an oyster farmer in a small fishing town in southern Australia, noticed that the waters around his oyster farm, which are typically pristine, had turned dirty brown.
He knew immediately what the problem was. A massive bloom of algae – it now covers 4,500 sq km, about six times the size of Singapore – had been spreading along the coast of South Australia state, and finally arrived in his home town of Stansbury.
Shortly after, state authorities advised Mr Bowley, whose Pacific Estate Oysters farm has more than 1.5 million oysters, that he could not sell his produce due to fears they could contain toxins.
Mr Bowley, 68, who is unable to sell his oysters for 82 days from July 25, told The Straits Times that he is considering giving up oyster farming and is looking for another job.
'It will be months before we open again – I am virtually bankrupt,' he said from Stansbury on the Yorke Peninsula. The town is directly opposite Adelaide across the St Vincent Gulf.
'The sea here is sick. There is nothing alive under the water. It will take years to recover,' added the oyster farmer of 19 years.
The spread of the algal bloom along the southern coast of Australia has not just ruined businesses such as Mr Bowley's, it is also affecting more than 450 species of marine life and threatening the region's exports of high-quality seafood.
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So far, the algae are believed to have killed more than 14,000 animals off the coast of South Australia, including fish, dolphins, eels, sharks, rays and crabs. At beaches across the state, fish, octopuses and other marine life have washed ashore, while damage to seagrass and reefs poses a long-term threat to marine ecosystems.
Mr Kyri Toumazos, deputy chairman of Seafood Industry Australia, which represents the nation's seafood trade, told ST that it is too early to assess the impact of the algal bloom on South Australia's seafood exports. This is especially as some fisheries, such as those for prawns, are seasonal and have not begun fully operating.
He said southern bluefin tuna and rock lobster supplies were largely unaffected, but molluscs and crabs were hit hard.
'It is early days yet to see the full impact on exports,' he added. 'Different regions are affected to varying degrees.'
South Australia produced about 72,900 tonnes of seafood in the year ended June 30, 2024 – worth A$478 million (S$402 million). It is a major exporter of southern bluefin tuna, oysters, rock lobster and prawns.
The top markets include Japan, Hong Kong, mainland China and Vietnam. According to Australian government data, Singapore is South Australia's fifth-largest seafood export market, buying A$27.6 million worth in the past year.
So far, the algae are believed to have killed more than 14,000 animals off the coast of South Australia, including fish, dolphins, eels, sharks, rays and crabs.
PHOTO: GREAT SOUTHERN REEF FOUNDATION IN AUSTRALIA
In response to ST queries, the Singapore Food Agency said: 'While Australia is a source of seafood, there has been no impact on supply to date. Singapore's sources are well diversified, and the industry is able to obtain their supply of seafood from different sources.'
South Australia's Minister for Trade and Investment, Mr Joe Szakacs, told ST that all South Australian seafood that is commercially available is routinely tested and safe to eat.
'Regular ongoing testing in open harvest areas ensures food safety standards are upheld.'
Despite the size of the bloom, it has not affected the entire state and is currently located around the capital, Adelaide, including many of its beaches, as well as the Fleurieu Peninsula, Yorke Peninsula, Kangaroo Island and the Spencer Gulf.
But the bloom, which is affected by weather and currents, is still evolving and changing direction.
A manager at South Australian fish market operator Safcol, Mr Ian Mitchell, said the bloom is having a devastating effect on the fishing industry.
'Areas that were once full of life have been devastated – they are just gone,' he added. 'Seafood is a big thing for (South Australia). We have got this disease in the water at the moment.'
The algae, which can damage the gills of fish and suffocate them, were first spotted off the coast in March and then began to spread. The massive bloom is believed to be due to a series of events, starting with inland floods in 2022 that collected organic matter, which then flowed into the ocean.
An upwelling of cold water in 2023-2024 brought the nutrients to the surface, and a marine heatwave in 2024 resulted in sea temperatures peaking at 2.5 deg C above normal levels. The warm water caused a blooming of the algae, which then spread and moved along the southern coast.
The authorities said the algae can cause flu-like symptoms but do not pose a serious risk to human health.
The bigger threat is to marine life and ecosystems.
A report by a group of environmental experts released on July 24 said the algal bloom marked 'one of the worst marine disasters in living memory'.
The report by Biodiversity Council, an independent expert group, warned that climate change is leading to marine heatwaves and increased risk of flooding that are creating conditions in which algal blooms can thrive.
It called for the federal government to curb carbon emissions, invest in research to identify species in need of immediate intervention, and establish a monitoring programme for the Great Southern Reef, which stretches 8,000km along the country's south coast.
'This algal bloom is a devastating example of how climate change has supercharged the potential for marine catastrophes,' it noted.
The federal and South Australian governments recently announced assistance packages totalling A$28 million to invest in research, clean-ups and support for the fishing and tourism industries.
A report by a group of environmental experts released on July 24 said the algal bloom marked 'one of the worst marine disasters in living memory'.
PHOTO: GREAT SOUTHERN REEF FOUNDATION IN AUSTRALIA
But the Federal Minister for the Environment and Water, Mr Murray Watt, rejected calls to declare the event a natural disaster, saying this declaration – which triggers funding – is used for events such as floods, cyclones and bush fires.
'This is an unprecedented event, and one of the difficulties has been understanding exactly what its impacts are and what sort of response is required,' he told reporters.
Experts believe the bloom will be reduced over the remaining winter months but could worsen in the coming summer as water temperatures increase.
Mr Bowley, who moved to the Stansbury area with his wife to start oyster farming because its water was so pristine, now fears his business has no future. He wonders whether future generations will be able to swim in the local waters.
'The water is brown and green – it's very dirty and smells very bad,' he said.
'I've never seen anything like it. We don't know what exactly caused this bloom, much less how we will avoid it in the future.'