Giant Australian cuttlefish disappearance in Whyalla, SA, linked to algal bloom
Consensus Summary
The giant Australian cuttlefish, which normally migrate in tens of thousands to the Upper Spencer Gulf near Whyalla for breeding each winter, have failed to appear in expected numbers in 2026, with only a few dozen spotted despite ideal water temperatures. Experts and tourism operators blame the historic algal bloom, which has persisted along South Australia’s coastline since March 2025, though the exact impact remains under investigation. The South Australian government imposed a 90-day ban on in-water recreational activities in the cuttlefish sanctuary zone to protect the critically low population, while tourism operators report significant financial losses, with estimates ranging from $400,000 to $1 million. Previous population crashes, such as the 2013 decline from 200,000 to 8,000, have occurred, but this year’s numbers are described as unprecedentedly low. While some officials remain cautious about attributing the decline solely to the algal bloom, marine ecologists and local experts increasingly point to it as the most plausible cause, with concerns about long-term survival of the species and the local tourism industry.
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Key details reported by multiple sources:
- Giant Australian cuttlefish normally arrive in tens of thousands in the Upper Spencer Gulf near Whyalla for breeding each winter, but only a few dozen have been spotted in 2026.
- The South Australian Research and Development Institute (SARDI) is conducting a full population survey of the cuttlefish, with results expected next week (late June 2026).
- A temporary 90-day ban on in-water recreational activities (e.g., diving, snorkeling, boat tours) in the cuttlefish sanctuary zone between Black Point and Stony Point in the Upper Spencer Gulf began on June 30, 2026.
- The algal bloom (Karenia cristata) is present along the South Australian coastline, including parts of the Spencer Gulf, with elevated levels (432,899 cells per litre at Proper Bay) reported in June 2026.
- The Whyalla Dive Shop and other tourism operators have cancelled or postponed cuttlefish-related tours due to the low numbers, with estimated losses of $400,000 (Manny Katz) and $1 million (Matt Waller) for the town.
- The government invested $700,000 in 2025 to install a 'bubble curtain' to protect cuttlefish eggs, but it was never activated because the algal bloom did not reach the Upper Spencer Gulf.
- Cuttlefest, Whyalla’s annual winter festival celebrating the cuttlefish, is ongoing despite the low numbers, with land-based activities continuing.
- Water temperatures in the Spencer Gulf are currently around 14 degrees Celsius, which is within the range for cuttlefish breeding, but the species has not arrived in expected numbers.
Points of Difference
Details reported by only one source:
- Tony Bramley, a long-time diver and environmentalist, noted that cuttlefish numbers crashed from 200,000 to 8,000 in 2013, with the cause never determined, but this year’s numbers are even lower.
- Whyalla Mayor Phill Stone initially dismissed the algal bloom as a cause, stating that seawater temperature was too high for cuttlefish migration, but later acknowledged the need for protection.
- Environment Minister Emily Bourke warned that breaching the exclusion zone could result in fines of up to $100,000.
- Matt Waller, a tour operator, suggested the ban could be lifted if cuttlefish numbers exceed 100,000 in official surveys.
- Associate Professor Zoe Doubleday, a marine ecologist at Adelaide University, stated that the algal bloom is 'likely' the cause of the cuttlefish decline, citing direct exposure or reduced food sources.
- The Guardian reported that divers observed cuttlefish appearing 'extremely skittish' and hiding under rocks, a behavior not previously documented.
- The Whyalla Dive Shop turned away $50,000 worth of bookings for the June long weekend due to the lack of cuttlefish.
- The stretch of coastline near Whyalla was added to the National Heritage List in 2023 due to the unique cuttlefish breeding event.
Contradictions
Conflicting information between sources:
- ABC’s Article 1 states that Whyalla Mayor Phill Stone initially said 'all the information we've been getting is that the algal bloom is not responsible,' while the Guardian and ABC’s Article 3 imply the algal bloom is the most likely cause of the decline.
- Article 1 (ABC) suggests water temperatures are within the ideal range for cuttlefish migration, while Article 3 (ABC) and the Guardian note temperatures are slightly elevated (14 degrees) and may be delaying migration.
- Article 1 (ABC) quotes Manny Katz as saying only 25–30 cuttlefish have been spotted, while Article 3 (ABC) and the Guardian describe sightings of 'a couple dozen' without a precise number.
- Article 2 (ABC) states the ban is for 90 days, while no other source confirms the exact duration beyond the immediate implementation.
Source Articles
Experts fear algal bloom to blame for disappearance of Whyalla's cuttlefish
Whyalla is the breeding spot for hundreds of thousands of cuttlefish, but the international spectacle has been cancelled after only dozens have been spotted this year.
Temporary ban to protect Whyalla's 'significantly low' cuttlefish numbers
From Wednesday, a 90-day exclusion will begin at the cuttlefish sanctuary zone between Black Point and Stony Point in South Australia's Upper Spencer Gulf.
No-show cuttlefish result in million-dollar loss for regional SA town
Whyalla has been forced to wind back services and let staff let go as its tourism industry suffers million-dollar losses from cuttlefish not making their usual migration.
Whyalla wipeout fears: cuttlefish usually gather in their thousands, but few have appeared since a massive algal bloom
Divers have observed just a ‘couple of dozen’ of the cephalopods along the heritage-listed Cuttlefish Coast in South Australia, causing locals and marine scientists to worry Get our breaking news email , free app or daily news podcast Mid-June is usually the peak time for giant Australian cuttlefish to gather near Whyalla, in South Australia’s Spencer gulf. Nearly every year, they come in their thousands – and sometimes hundreds of thousands – to assemble in the shallows to breed. It’s a globall