Giant Australian Cuttlefish Face Potential Collapse in Upper Spencer Gulf

A four-person dive team from the ecological not-for-profit Eyrelab surveyed the Point Lowly breeding grounds in July and counted only 44 adult cuttlefish and 440 eggs, a stark contrast to the millions of eggs normally observed. The unusually low sighting prompted a press conference on 30 June, where Prof Mike Steer, executive director of the SA Research and Development Institute, reported “less than 50 animals” had been seen earlier in the season. The state government responded on 1 July by imposing temporary restrictions on swimming and snorkelling to reduce disturbance to the remaining breeders and their eggs.

The Guardian

Giant Australian cuttlefish congregate in the upper Spencer Gulf each breeding season, with historic survey estimates ranging from a low of 13,500 in 2013 to a high of 247,000 in 2020. The most recent pre-bloom figure was 63,000 in 2025. These fluctuations have traditionally been attributed to variable environmental conditions, but the 2026 counts represent the lowest abundance recorded to date.

The Guardian

Australia’s first toxic bloom of Karenia cristata algae began in March of the previous year and remains present along parts of the South Australian coastline. Testing has detected elevated Karenia levels at seven of 32 sites on the Eyre Peninsula and two of 19 sites on the Yorke Peninsula, making it the largest and most destructive algal bloom in the nation’s history. Researchers suggest the bloom could have killed cuttlefish directly, altered their food supply, or impacted predator dynamics, though definitive causality is still under investigation.

The Guardian

Prof Mike Steer emphasized that the raw counts require further analysis before an official population estimate can be released. A state government spokesperson noted that cuttlefish numbers naturally rise and fall from year to year due to environmental factors. Stefan Andrews of the Great Southern Reef Foundation urged the federal government to consider listing the species as threatened under the Environment Protection and Biodiversity Conservation Act, citing the “catastrophic decline.”

The Guardian

• “This is by far the lowest abundance that we’ve had on record,” — Manny Katz, diver and Eyrelab director

The Guardian

• “The algal bloom reached the giant Australian cuttlefish breeding site at Point Lowly in upper Spencer Gulf and, while it appears likely the algal bloom has impacted cuttlefish numbers, researchers are working to determine whether this contributed to the reduced population.” — Assoc Prof Zoe Doubleday, a cuttlefish and octopus expert at Adelaide University

The Guardian