Giant Australian Cuttlefish Decline: Only 44 Counted in Dive 2026

The giant Australian cuttlefish population is facing a catastrophic decline, with a recent dive survey counting only 44 individuals off the coast of Whyalla, sparking urgent calls for government action. This iconic species, known for its spectacular annual breeding aggregation in the upper Spencer Gulf, has seen numbers plummet from historic highs, raising fears of an ecological disaster. Scientists and divers are demanding transparency on official population estimates as the clock ticks on this marine marvel.

Why the Giant Australian Cuttlefish Decline Matters

The giant Australian cuttlefish (Sepia apama) is the world's largest cuttlefish species, and Whyalla is the only place on Earth where they gather en masse to breed. Each year, tens to hundreds of thousands of these creatures assemble along a rocky reef, creating a unique natural spectacle that draws tourists and researchers alike. The recent dive survey, conducted by the ecological not-for-profit Eyrelab in July, found only 44 individuals and 440 eggs, where millions of eggs would normally be present.

This dramatic drop follows a devastating toxic algal bloom that has impacted the state's marine environment. Manny Katz, diver and Eyrelab director, described the finding as “by far the lowest abundance that we’ve had on record,” noting that the few cuttlefish observed were “not out and about – they’re hiding.” The low numbers have already forced tourism and dive operators in Whyalla to cancel the 2025 cuttlefish season, and the South Australian government has imposed temporary restrictions on swimming and snorkelling to protect breeding animals.

Historical Population Trends and Current Crisis

To understand the severity of the current decline, it's essential to look at historical survey data. Since 1998, populations have fluctuated widely, but never have they dropped to such critical levels. The table below compares key survey years:

The 2025 count of 44 individuals is a staggering 99.98% drop from the 2020 peak. Even in 2025, official estimates had predicted over 63,000 cuttlefish, but the actual observed numbers are far lower. Marine biologist Stefan Andrews from the Great Southern Reef Foundation has called on the state government to release official figures promptly. “It’s clear that it’s going to be bad news,” he said. “People need to know just how bad the situation is. Let’s see it, and not sit on it too long because the clock is actually ticking.”

Key Takeaways from the Dive Survey

• Only 44 giant Australian cuttlefish were counted in the July 2025 dive survey, the lowest on record.
• Only 440 eggs were found, compared to millions in normal years, indicating breeding failure.
• The toxic algal bloom is believed to be the primary cause of the decline.
• Tourism and dive operations in Whyalla have cancelled the 2025 season.
• Government restrictions on swimming and snorkelling are in place to protect remaining cuttlefish.

What This Means for Conservation and the Future

The collapse of the giant Australian cuttlefish population is not just a local issue; it has global implications for marine biodiversity. The species plays a vital role in the Spencer Gulf ecosystem, and its loss could trigger cascading effects on other marine life. Conservationists are urging immediate action, including enhanced monitoring, habitat protection, and research into the long-term impacts of algal blooms.

While the situation appears dire, there is hope. Historical data shows that cuttlefish populations can recover if conditions improve. For example, after the 2013 low of 13,500, numbers rebounded to over 247,000 by 2020. However, the current decline is far more severe, and recovery may take years. The South Australian government's response will be critical in determining the species' fate.

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