Scientists and divers have called on the South Australian government to release official cuttlefish population estimates amid fears of a \u201ccatastrophic\u201d decline, after a dive survey counted only 44 individuals.<\/p>\n
Each year, tens to hundreds of thousands of giant Australian cuttlefish assemble off the coast of Whyalla<\/a>, in the upper Spencer Gulf, to breed \u2013 the only place<\/a> globally where cuttlefish gather en masse.<\/p>\n In surveys dating back to 1998, populations ranged from a low of 13,500 in 2013 to a high of 247,000 in 2020. More than 63,000 were recorded in 2025.<\/p>\n Numbers this year were widely expected to be the lowest on record, after the devastating effects of the toxic algal bloom<\/a> on the state\u2019s marine environment.<\/p>\n Cuttlefish usually die after breeding, making the population heavily dependent on the success of each breeding season. Photograph: Stefan Andrews<\/p>\n The team of four divers from ecological not-for-profit Eyrelab, who surveyed the coastline in July, also counted only 440 eggs where there would normally be millions.<\/p>\n \u201cThis is by far the lowest abundance that we\u2019ve had on record,\u201d said Manny Katz, diver and Eyrelab director, who added that the few dozen cuttlefish they saw were \u201cnot out and about \u2013 they\u2019re hiding\u201d.<\/p>\n Stefan Andrews, a marine biologist from the Great Southern Reef Foundation, called for the state government to release the official figures.<\/p>\n \u201cIt\u2019s clear that it\u2019s going to be bad news,\u201d he said. \u201cPeople need to know just how bad the situation is.<\/p>\n \u201cLet\u2019s see it, and not sit on it too long because the clock is actually ticking.\u201d<\/p>\n The historically low numbers led tourism and dive operators in Whyalla to cancel their cuttlefish season in June. On 1 July, the state government introduced temporary restrictions on recreational activities such as swimming and snorkelling, to minimise disturbance to breeding cuttlefish and help protect their eggs and hatchlings.<\/p>\n At a press conference on 30 June, Prof Mike Steer, the SA Research and Development Institute\u2019s executive director, said \u201cless than 50 animals\u201d had been observed earlier in the season. Those were \u201craw counts\u201d, he said, with further monitoring and analysis required before providing a population estimate.<\/p>\n A state government spokesperson said surveys had now been completed, and 2026 estimates would be released after review.<\/p>\n \u201cCuttlefish numbers naturally rise and fall from year to year\u201d, driven by environmental conditions, the spokesperson said. \u201cThe 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.\u201d<\/p>\n Assoc Prof Zoe Doubleday, a cuttlefish and octopus expert at Adelaide University, said the bloom may have killed cuttlefish directly or changed the availability of their food supply \u2013 or their predators\u2019 food supply.<\/p>\n Cuttlefish live short lives<\/a> and adults usually die after breeding, making the population heavily dependent on the success of each breeding season.<\/p>\n Australia\u2019s first bloom of toxic Karenia cristata algae, which began in March last year, is still present along parts of the South Australian coastline. It is the largest and most destructive algal bloom<\/a> in the nation\u2019s history.<\/p>\n The latest testing results show elevated levels of Karenia algae at seven of 32 testing sites on the Eyre peninsula, and two of 19 sites on the Yorke peninsula.<\/p>\n