Australia’s annual giant cuttlefish breeding aggregation on South Australia’s Cuttlefish Coast has fallen to its lowest recorded level, raising fears of a severe decline in the species. Officials estimate that only 1,811 animals arrived this winter, compared with 63,000 last year, and conservationists are calling for the cuttlefish to be listed as endangered.

The decline is being linked to a toxic algal bloom affecting South Australia’s coast for more than 18 months, with ocean warming, marine heatwaves and nutrient pollution cited as contributing factors. Surveys found only about 440 eggs along eight kilometres of reef, rather than the millions normally expected; because adults live for only 12 to 18 months and usually die after breeding, this season could heavily affect next year’s population.