As Coles and Woolworths prepare for their annual general meetings, hundreds of their own shareholders have drawn battle lines in defence of an ancient species.
Investors are imploring the retailers to stop selling salmon farmed in Tasmania's remote Macquarie Harbour.
The shallow, narrow-necked waterway is the only place on earth where the Maugean skate exists but the species, a type of ray which dates back 60 million years, is teetering on the brink of extinction.
A range of factors have contributed to its precarious position but federal conservation advice ranks salmon farming as the main human contributor to poor water quality and that is the primary threat to the skate's existence.
Since about May last year, the supermarket giants have been fielding pointed questions about why they continue to sell salmon farmed in the harbour.
That's when scientists from the University of Tasmania's Institute for Marine and Antarctic Studies called for urgent action to save the species on the back of evidence of a dramatic population plunge.
Subsequent estimates have suggested there may be just 40 to 120 adults left in the wild and federal authorities will shortly decide if the species should be uplisted to critically endangered.
Meanwhile, the Australian government is spending millions on a captive breeding program as the federal environment minister - who has promised no new extinctions - reviews salmon farming in the harbour.
And the salmon industry is co-funding an artificial oxygenation trial after previous increases in fish farming were linked to problematic drops in available oxygen.
With all that going on, some investors are asking why Macquarie Harbour salmon is still for sale at Coles and Woolworths stores across the nation, and why it's not clearly labelled so shoppers know what they're buying.
More than 100 investors, in each of the retailers, are now formally pressing for change via resolutions that demand they stop sourcing Macquarie Harbour salmon for their own-brand products by April.
Another resolution calls on them to report on the impact farmed seafood used in their own-brand products is having on federally listed endangered species.
Statements by concerned shareholders warn that without change, the companies and their investors face a catalogue of risks.
They include a public perception of greenwashing, reputational damage and a loss of social licence and shareholder skittishness over the risks of being associated with "a foreseeable extinction event".
Activist share trading platform SIX is part of the campaign and CEO Adam Verwey says the shareholder resolutions aimed at preventing an extinction are a world first.
He's realistic about the outcomes, with Coles doing as he expected this week and advising in its AGM notice that the board won't support the resolutions.
But he says there are powerful signals for both companies when a shareholder like Betashares, one of Australia's leading fund managers, takes the unusual step of declaring its support in advance of the AGMs.
Trevor Thomas is the managing director of Ethinvest, Australia's oldest ethical investment advisory company managing $1.2 billion for 1000 clients.
A quarter of the shareholders behind the resolutions are Ethinvest clients - a mix of longer term supermarkets investors and new ones who've bought shares to be part of the skate campaign.
Mr Thomas alongside Mr Verwey has been in on engagement meetings with Coles and Woolworths and says they accept the skate is in trouble and there's a problem to be fixed.
"They were clear that they were committed and that they were having serious internal conversations, and that it's a complex issue because there were a lot of stakeholders."
He says the companies expressed a desire for a just transition to help affected workers find new employment but also acknowledged there were "different priorities for state and federal governments".
"It's a contested area we understand, but as the biggest customers they have got disproportionately powerful voices, and that's what we were trying to drive home to them."
Mr Thomas sees parallels between the current campaign and the one Market Forces led against Australia's big banks over climate action.
"The major banks were hostile to the resolutions put by Market Forces at the outset.
"They were polite in face to face meetings - I participated in a number of them - but took a hard line against the resolutions in their AGM papers.
"Coles seems to be taking a similar approach, which is very encouraging, given that all the major banks have conceded Market Forces played an important role in accelerating their evolution of climate policies."
Coles recently released its 2024 sustainability report, with Coles Group chairman James Graham and CEO Leah Weckert saying: "We have been steadily reducing the volume of salmon we source from Macquarie Harbour, with plans to continue this transition in the coming year".
But Coles has not answered AAP's questions about how much less salmon has been sourced from the harbour, or what its reduced target is for the year ahead.
Salmon Tasmania is an umbrella group for Tasmania's three big producers: Tassal, Huon and Petuna, which all farm salmon in Macquarie Harbour.
CEO Luke Martin says he's not aware of Coles reducing or cancelling any supply contracts affecting Salmon Tasmania's three member companies but wouldn't expect that level of oversight given it is sensitive information.
But he says it's a fact that Macquarie Harbour salmon, as a proportion of state production, has been declining and people can take what they want from that.
Current production in the order of 9000 tonnes a year is less than half what it was eight years ago.
Mr Martin says the industry believes current production is sustainable and cited recent reports by Tasmania's Environmental Protection Authority showing oxygen levels are the best they've been in years.
University of Tasmania Associate Professor Jeff Ross has spent years studying Macquarie Harbour's health.
He says improvements across the entire harbour can be attributed to good, natural recharging conditions over three of the last four summers, and the salmon industry being ordered to cut production a few years back.
When AAP asked Coles about the resolutions, it said it was aware of stakeholder concerns about the impact of salmon farming and was taking the issue very seriously.
"We acknowledge the government-led consultations currently underway and we are continuing to engage with a range of stakeholders, including suppliers and NGOs," it said.
It repeated its assertion that the volume of salmon sourced from the harbour has been reducing with the "transition" to continue in the coming year, without providing figures.
The Woolworths Group also says it's taking shareholder concerns seriously but is also "sensitive to the employment, community, economic and commercial impacts of what this resolution calls for".
It says it's continuing to engage with interested parties while awaiting the outcome of the environment minister's review.
"We believe it is not only prudent, but responsible as a large retailer, that we await the outcome of the government review and scientific research currently underway."
Coles and Woolies say only a portion of the salmon they sell comes from Macquarie Harbour.
