Want to eat a healthy and sustainable fish diet? Drop the farmed salmon

Eating seafood is good for us – the NHS recommends two portions of fish a week, with one of them being a portion of oily fish – but for those of us who choose to eat fish, we don’t want it to be at the expense of the health of the oceans and the opportunity for future generations to enjoy their bounty. More than half of us say sustainability affects our shopping decisions when it comes to seafood.

While there are lots of ways to eat protein – with plant-based sources posing the least burden on our environment, it can be difficult to access some micronutrients, like omega 3, without eating some seafood. In this context, farmed fish, like farmed salmon, can seem like the best of both worlds – high levels of micronutrients like omega 3, without putting any greater burden on wild fish. Right?

Unfortunately, the reality is not nearly as clear cut. The reason farmed salmon, especially Scottish farmed salmon, has high levels of omega 3 is because of what its fed – fish oil made from hundreds of thousands of tonnes of wild fish, such as sprat, herring, sardines and anchovies. Most of this wild fish could be eaten directly by people.

We examined whether eating farmed salmon fed on wild fish was a good way to get micronutrients into our diets. We calculated the total micronutrient output of the Scottish farmed salmon industry – salmon from Scotland tends to contain higher levels of micronutrients because it is fed on higher levels of fish oil than salmon produced in Norway or Chile. We then compared this to a model of the micronutrients that would be available if we ate some of the wild fish that is fed to Scottish salmon.

The results are stark: if we ate some of the diverse and delicious wild fish – like herring, sardines and anchovies –  we could still access the same level of micronutrients produced by the Scottish salmon industry while leaving 59% of the fish caught to feed that industry in the sea. That’s over 270,000 tonnes of wild fish every year.

What’s more, we can still eat some farmed salmon: in our model we included some salmon farmed using fish oil made from by-products (the heads, bones and other trimmings) of fish caught to be eaten by people. This might mean a much smaller Scottish salmon industry – but it would also mean salmon farming that truly existed within natural limits, at least as far as marine ingredients in feed is concerned.

Eating wild fish and salmon isn’t the only way to get high quality micronutrients into our diets: farmed mussels (delicious with a garlic sauce and chips!) are very nutritious and high in omega 3. In addition, mussels don’t need feed – they live off plankton and other microscopic particles in the water. If we added some mussels to our diets, in addition to a range of small wild fish, we could leave 77% of wild fish caught to feed Scottish salmon industry in the sea, and still have a very healthy seafood diet.

In other words, despite the messages of the global salmon farming industry, catching fish to feed farmed salmon is not the answer to eating healthily and sustainably.

The salmon farming industry is aware of this contradiction at the heart of their production model. The industry has been exploring alternatives to ingredients made from farmed fish – but none are yet available at scale, and there are no guarantees that these won’t pose other environmental challenges (such as greenhouse gas emissions involved in producing them). Instead, the main industry response to challenges to its reliance on wild fish has been to hold up certification schemes, such as MSC and the MarinTrust. When we asked all six Scottish salmon companies for transparency on how and where they sourced their wild fish, only three replied in any detail: we’re grateful to the three companies who did engage – Grieg Seafood, MOWI and Loch Duart – for an insight into how these companies set standards for their feed.

What this engagement revealed is that salmon farming companies’ feed sourcing policies rely heavily on certification as a means of ensuring that the wild fish they use has been ‘sustainably’ caught. This opens up a further dilemma. The effectiveness of certification schemes at preventing overfishing is controversial. Several fisheries listed by the FAO as some of the most over-fished regions in the world are also certified for fish oil and fishmeal production by the MarinTrust (for example, Turkey and Morocco). The certification of new fisheries is fundamentally driven by market demand, and with an ever-rising demand for fishmeal and fish oil – not just from the salmon industry but also from the petfood, chicken and pig feed industries – there is limited power to check the pressure to certify new fisheries, even when they may not be sufficiently stable to warrant this. As a result, we are recommending that certification is only used as a tool to assess fish intended for direct human consumption.

Beyond the ins and outs of different sourcing policies, an important question remains: if there is a finite amount of sustainably-caught fish available in the world – and ever-increasing demand for the nutrients it contains – how should we make best use of it?

While to companies involved in the global aquaculture industry some fisheries are highly suitable to commodification to make fish feed ingredients, to many communities these fisheries are or could be a source of nutrition and livelihood. Certification of reduction fisheries is being used as tool to justify the reclassification of fish away from human food and towards animal or fish feed: this approach essentially transfers nutrients around the globe, in the process removing them from more local supply chains and redirecting them towards international supply chains where they can deliver greater financial value.

In asking the question – should we eat fish or not we oversimplify the issue; it is vital to consider what fish is eaten and who gets to eat it. We have delved deep under the surface of the global salmon farming industry, to get to grips with the flow of nutrients around the world and which currents are most likely to support both good human health AND the long-term health of our oceans. To read the full reports click here.