Home / Environment / South Australia's Cuttlefish Crisis: Numbers Plummet
South Australia's Cuttlefish Crisis: Numbers Plummet
10 Aug
Summary
- A dive survey found only 44 cuttlefish, a drastic drop from hundreds of thousands.
- A toxic algal bloom is suspected of causing the catastrophic decline in numbers.
- Scientists urge the government to release official population estimates immediately.
Scientists and divers are urgently calling on the South Australian government to release official estimates for the giant Australian cuttlefish population. Recent surveys in the upper Spencer Gulf, the only place globally where these cuttlefish gather en masse to breed, revealed alarmingly low numbers. One dive survey counted just 44 individuals, a stark contrast to historical populations that ranged from tens of thousands to over 247,000.
The suspected cause for this catastrophic decline is Australia's largest and most destructive toxic algal bloom, Karenia cristata, which began in March 2025. Researchers are investigating whether the bloom directly killed cuttlefish or impacted their food supply. The species' short lifespan makes them heavily reliant on successful breeding seasons.
Tourism and dive operators in Whyalla have already canceled their cuttlefish season due to the low numbers observed. In response, the state government implemented temporary restrictions on recreational activities to minimize disturbance to any remaining breeding cuttlefish and protect their eggs. Official population estimates for 2026 are expected to be released after a review, but experts stress the urgency of understanding the full extent of the crisis.
