Sydney’s beloved blue gropers are disappearing. Can we slow their demise?

Numbers of Sydney’s beloved eastern blue gropers have halved since 2008 as a likely result of climate change, bolstering the case for the NSW government to make its line-fishing ban permanent.

Last February, NSW Agriculture Minister Tara Moriarty announced a total ban on fishing blue gropers for an initial 12-month trial, following community outrage when a spearfisher killed “Gus”, a blue groper, in Cronulla, and another person speared three blue gropers in Jervis Bay.

A blue groper in Clovelly, Sydney, in December 2023.Credit: Janie Barrett

The ban will expire this month unless the government extends the trial or makes it permanent. Spearfishing was outlawed in 1969, and commercial fishing is also banned but recreational fishing with a rod or line was allowed until last year.

“During this 12-month trial period, the government has consulted stakeholders and the broader community, plus fisheries scientists have been undertaking a comprehensive stock assessment of the blue groper,” Moriarty said. “An announcement on this matter will be made soon.”

Government records show 21 offences involving blue gropers from March 1, 2024, to January 12, 2025, including six people cautioned and 15 fined. The full records for summer are not yet available.

From March 1, 2023, to February 28, 2024, there were 30 offences including two prosecutions. In the 12 months before that, there were 36 offences.

Blue gropers, known formally as Achoerodus viridis or informally as the puppy dogs of the sea for their curious, friendly nature – are the official state fish of NSW.

The research was conducted mostly by scientists at the NSW Department of Primary Industries and Regional Development who published their findings in the CSIRO peer-reviewed journal Marine and Freshwater Research this month.

Blue gropers can grow up to 1.2 metres long and live for 35 years. They are a hermaphrodite species, the paper says. The fish is brown and female up to about half a metre in size and changes to male with distinctive iridescent blue colouring as they grow bigger.

The scientists noted that as a long-lived, slow-growing fish with late sexual maturity (10 years for males), the species is particularly susceptible to overfishing.

The population review using data from 2008 to 2020 found that the Tweed bioregion in northern NSW had the lowest numbers of blue gropers, which the scientists expected because of warmer waters. The fish were most abundant in the Batemans bioregion off the South Coast, where water was cooler.

A blue groper known as “Bluey” pictured at Clovelly in January 2020.Credit: James Alcock

Over the 12-year period, populations of blue gropers on shallower reefs declined by about 50 per cent in the Manning bioregion (Mid North Coast) and the Hawkesbury bioregion (Greater Sydney from roughly Shellharbour to Newcastle). The abundance of the species in these areas is similar to northern NSW.

The scientists found blue gropers were doing better in deeper reefs where the water was cooler.

“Whereas there is evidence for significant declines in shallow waters of the Manning and Hawkesbury, population abundances on deeper inshore reefs appear to have been comparatively stable over the past 12 years,” the paper says.

“The most likely cause of the observed declines in shallow waters of the central NSW bioregions is ocean warming on this section of the coast, although additional research is required to further confirm these climate-related relationships.”

Sightings of blue gropers have reportedly increased in Victoria and Tasmania, which suggests the habitat could be moving south as climate warms.

The paper found the average population across the state was stable, despite the variability in different bioregions and depths of reef.

Australian conservationist, photographer and filmmaker Valerie Taylor said blue gropers were beloved by the public because they were friendly and able to remember individual humans, so people could befriend them like kookaburras or possums.

“Generally, a big blue fish swims up and goggles at you, and … if you turn over a stone or two so it can find a crab, you would have a friend for the whole dive,” Taylor said. “There’s not many places where you can go into the wilderness – the bush or the desert or the ocean – and make friends so easily.”

Taylor said the iconic fish should be protected, adding that catching a male blue groper was unlikely to be an accident given its distinctive size and colour.

She also hoped the government would end the use of shark nets installed at 51 NSW beaches every summer, which is under review. The evidence suggests other shark management methods such as SMART drumlines and drone surveillance are more effective.

“Once you’ve seen a baby dolphin drowned in the shark nets, covered in scratches where its mother has tried to pull it out, you hate the things,” Taylor said.”

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