Farmed salmon called into question - so is it safe to eat?

Yahoo

05-03-2025

Over the last two weeks, many Aussie consumers have been questioning whether they want to continue eating farmed salmon. Thousands of the fish have died inside Tasmanian aquaculture facilities over the last fortnight, sparking concern about pollution, the use of antibiotics, and the prevalence of disease.
But switching to wild caught alternatives in Australia isn't an option for most, because it's not locally produced. The large foreign-owned aquaculture ventures around Tasmania's coastline supply around 90 per cent of the Atlantic salmon consumed across the nation.
Very little wild Atlantic or Pacific salmon is imported fresh from its native ranges around North America, Europe and Russia. But is wild salmon more nutritious or environmentally superior?
According to Melbourne University seafood expert Professor Giovanni Turchini, the answer is complicated. He is privy to the most up to date research on the seafood and aquaculture industries, and heads the multidisciplinary research team at AquaS, the Aquaculture Sustainability laboratory.
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When it comes to Omega 3, then farmed fish generally have more of the most beneficial long-chain fatty acids EPA and DHA per milligram, and these are thought to be most beneficial to human health. But the reason farmed fish have more is that they're much fatter than their leaner wild cousins.
'It's important to educate the consumer that there's no good or bad. What is good for one person may be not good for another,' he said.
'For example, a nice fresh salad with a lot of vegetables is good for us when compared to a burger. But if you go to Central Africa where they lack protein, a burger is much better than a salad.
When it comes to contaminants and pollutants being absorbed by salmon from the water they inhabit, Turchini notes they both have 'very small' risks.
'Wild salmon might have the risk of more contaminants. You don't know where they grow, so there could be environmental contaminants like PCBs, mercury, or dioxins, which in farm fish, you don't find it because typically there's a lot of environmental control of the quality of the water and the food,' he said.
'However, in farmed fish you could have other contaminants like antibiotics if they're not used properly.'
Similar to most other fish, salmon flesh is naturally white. But like flamingos, its flesh turns pink due to the consumption of small crustaceans which contain astaxanthin, a carotenoid molecule similar to what we find in carrots.
Farmed fish are mostly fed on a diet of pellets. 'With chickens, they use these molecules that increase the color of the yolk. The same happens in fish. Astaxanthin is a powerful antioxidant that's similar to Vitamin A and is very good for our health and good for the fish because it helps them cope with environmental stress or heatwaves,' Turchini said.
And the pellets can contain either natural shrimp astaxanthin or a synthetic alternative.
'Some consumers are worried about this synthetic astaxanthin, but it's exactly like all the multivitamins they buy – all are synthetic. They are chemically identical to the natural one, and it's the reality in all food systems, not just salmon,' Turchini said.
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While the scale of the recent fish deaths in Tasmania is unprecedented, but Tasmania's $1 billion salmon-farming industry has been controversial.
Prime Minister Anthony Albanese and Opposition Leader Peter Dutton are diehard supporters of the industries, but there have been ongoing concerns about pollution from the farms. In Macquarie Harbour, the resulting lower oxygen levels have led to the near extinction of a native fish, the maugean skate, that inhabits the same waters.
There have also been ongoing concerns about salmon farmers deterring seals away from the salmon with explosives and rubber bullets.
Turchini believes another problem with farmed salmon is that farmers need to capture and grow food to feed the salmon, including chicken, grain and soy. But he believes it takes the pressure off wild populations, some of which have been over-fished.
'There's also the issue of bycatch – catching additional species we don't want. And then with trawling there's habitat destruction,' he said.
'But then with farmed fish there is the risk of escape. And those salmon could have an impact on the wild populations of fish.'
According to Turchini, the main difference between salmon raised in Australia and New Zealand is the species. Most fish produced at home is Atlantic salmon while across the ditch it's King salmon, but they are farmed in a very similar way.
'Nutritionally they are similar on all aspects, as they are very similar species, and they are fed with basically the same feed and farmed in similar high-quality waters, with the only difference being that New Zealand king salmon contains more fat, and thus also more Omega 3. For that it is particularly appreciated on some markets, and less on others,' he said.
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