It might be easy to get your hands on a can of tuna, but it's much harder to work out if it's a fish that was caught sustainably.
That's according to research from the global flagship organisation promoting sustainable fishing, the Marine Stewardship Council (MSC).
Fresh data shows that most Australians want to buy sustainably sourced tuna but are struggling to identify brands that don't cause adverse impacts to marine environments.
The study, which surveyed 1,023 people, found 57 per cent of Australians said they seek out sustainably sourced, independently certified tuna when shopping.
However, the MSC said 39 per cent of canned tuna products on supermarket shelves in Australia were branded with its "blue tick" sustainability credential between 2021 and 2022.
The study also noted millions of Australians who regularly eat tinned tuna are confused by the various labels indicating strong environmental standards, and 43 per cent of tuna eaters don't recognise eco-labels such as the blue tick.
"People get bombarded by a range of certifications and quite often they're using outdated information," said Tuna Australia chief David Ellis.
"Consumers are looking for more sustainably sourced produce, and that in itself is a wake-up call for fisheries that aren't innovating to become sustainable."
Greenpeace hasn't ranked major canned tuna brands since 2017, after they all agreed to stop using wooden rafts blamed for overfishing, known as fishing aggregating devices.
Nearly half of tuna companies around the world are involved in MSC assessments, making them eligible for a blue tick once they meet a benchmark sustainability rating.
The rating is based on analysis of tuna stock health, impact on ecosystems, and the management of fisheries.
Last year, the Food and Agriculture Organization of the UN released a report showing more than a third of fisheries around the world have been fished beyond sustainable limits.
Anne Gabriel, MSC's Oceania program director, said 45 tuna fisheries around the world are MSC-certified.
With such a large appetite for sustainably sourced tuna, Ms Gabriel is urging tuna companies to help consumers "not feel guilty" about their choice of canned tuna by making their environmental credentials clearer.
"Sustainability is no longer a luxury," she said.
"There is a growing level of discernment and awareness among Australians about the environmental impact of what they're eating."
Blue tick a silver bullet for tuna packaging?
The average Australian household eats 36 cans of tuna per year, and almost three-quarters of Australian adults are tuna eaters.
So should millions of Australians start looking out for the MSC's blue tick next time they're in the supermarket?
Adrian Meder, the sustainable seafood program manager at the Australian Marine Conservation Society, said the decision isn't so easy.
The conservation society uses a separate traffic light rating system, ranking seafood products under the categories green (better choice), amber (eat less), or red (say no).
Mr Meder said he was concerned about the sheer number of fisheries eligible for the MSC blue tick.
"We're not entirely comfortable with the claim that nearly half of the world's tuna fisheries are genuinely sustainable," he said.
"There are blue tick products that are listed under all three categories of the GoodFish guide, red, amber, and green."
The conservation group is restricted to providing analysis of fresh tuna, more commonly found at a fish market or behind a supermarket's seafood section.
Canned tuna found in the aisles, which have travelled from large-scale fisheries, don't fall under the GoodFish traffic-light rating system.
Mr Meder said the Australian Marine Conservation Society wants to broaden its scope to provide its own third-party credential of canned tuna products, in a bid to ensure "industrial tuna fishing doesn't pose any threat to biodiversity and populations of endangered species, such as dolphins and turtles".
The Australian Consumer Watchdog launched a sweeping crackdown on "greenwashing" earlier this year, vowing to hold businesses accountable for making broad claims about their eco-credentials.
Kiarne Treacy, founder and chief of Sustainable Choice Group, said eco-labels from third-party accreditations and business's self-made claims were both under the microscope.
"These eco-labels have the power to guide more sustainable consumption or mislead if used incorrectly," she said.
