Giant cuttlefish numbers in South Australia plunge 97% amid algal bloom concerns

South Australia's Department of Primary Industries and Regions reported that the giant cuttlefish population in Spencer Gulf has dropped by 97%, with counts falling from 63,000 last year to 1,811 this year. The decline coincides with a severe algal bloom, which scientists believe may have impacted both adult cuttlefish and their offspring. Marine biologists surveyed eight kilometres of shoreline and recorded only 440 eggs, far fewer than expected for a healthy breeding event.

Environmental groups and experts, including Manny Katz, are urging that the species receive formal endangered status to unlock additional funding and monitoring. The federal environment minister has asked the Threatened Species Scientific Committee to assess a listing under the EPBC Act. A collaborative research program involving the state government and Adelaide University will track the cuttlefish population until 2028, funded in part by a $165 million algal bloom response fund.