Are farmed fish a sustainable choice? Many still depend on wild-caught fish for feed – algae grown on Scottish whisky industry waste could change that.
Aquaculture is now the world's largest source of fish for human consumption, outpacing wild catch globally.
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But the industry has a hidden problem: farmed fish, especially salmon, are carnivores that need omega-3 fatty acids – and almost all of that omega-3 comes from fish oil, which itself is extracted from wild-caught fish.
"The sustainable limits of what you can catch out of the ocean at the moment have been reached," Douglas Martin, founder and CEO of MiAlgae, tells Euronews Earth. "You can't physically catch any more out of the seas."
The result is a cycle that undermines the environmental credentials of farmed fish: the more aquaculture grows, the more pressure it places on already-strained wild fish populations.
Going back to the source of omega-3
Martin's answer is to go further down the food chain – all the way to microalgae. Oily fish do not actually produce omega-3 themselves; they accumulate it from the algae they eat. MiAlgae cuts out the middle step entirely.
"The algae are the ones that actually produce the omega-3s," Martin tells Euronews Earth. "If you can produce the algae and you can grow that algae, you can get the omega-3s without actually having to go through the whole food chain."
The challenge that has frustrated researchers for years has been cost. Growing algae on high-grade feedstocks makes the economics unworkable when competing against cheap wild fish oil. MiAlgae's solution is to use low-value industrial byproducts as the algae's food source – specifically, the liquid waste from Scotch whisky distilleries.
Whisky production generates an eight per cent alcohol beer, from which distillers extract the alcohol. The remaining 92 per cent – produced in billions of litres every year across Scotland – is largely low-value waste.
MiAlgae feeds that liquid to algae cells in large stainless steel tanks, harvesting the resulting biomass as a direct replacement for fish meal and fish oil.
"It's a bit like brewing," Martin explains. "You take a very small number of algae cells and you take all the whisky byproducts and some other bits and you put them into these big stainless steel tanks and you let the algae feed on all of that nutritious goodness."
Scaling up production of dried algae
MiAlgae's current product is dried algae, bagged and shipped to aquafeed and pet food manufacturers as a drop-in substitute for wild fish ingredients. The pet food sector is the company's primary market for now, with aquafeed customers also in the pipeline.
The company is currently building out its first full commercial production site, which Martin says will produce thousands of tonnes of product per year – significant, but still a fraction of global demand.
"In the omega-3 world that's a good start, but a drop in the bucket," he tells Euronews Earth. "So we've got lots more fish to save still."
On price competitiveness, Martin acknowledges the challenge of matching fish oil at current scale, but frames the comparison in terms of value per unit of omega-3 delivered. "We're looking to be cost parity with any fish oil that's coming out of the world," he says.
MiAlgae reached the finals of the Earthshot Prize in 2024 – a platform Martin credits with boosting the company's credibility. "Having the Earthshot Prize behind us has been a huge win for us," he says.
With commercial scale production on the horizon and industry interest growing, MiAlgae is positioning itself as a systemic alternative to one of aquaculture's most entrenched – and least visible – sustainability problems.
