The human factor | What is the best salmon for the environment?

“Which is less damaging to the environment: farmed salmon or wild salmon? », asks Sylvie.

“There is no perfect answer, both have an impact,” immediately says Olivier Morissette, professor of biology at the University of Quebec in Chicoutimi.

Whether fishing or farming, at sea or on land, each method has its advantages and disadvantages.

Wild salmon

Wild salmon has the advantage of being less expensive than farmed fish, and of avoiding the issues associated with captive breeding.

It can be beneficial from an environmental point of view, but its sustainability depends on the way it is fished – and in particular, the fishing quotas set by governments – but also on the health of its ecosystems. In particular, “certain species of salmon such as chinook are particularly endangered,” recalls Sylvain Charlebois, director of the agri-food analytical sciences laboratory at Dalhousie University.

The place where it is fished can also play a role: if it is in the open sea, it requires more fuel for the boats; but if it is at the entrance to the rivers, this can be problematic for the species if the salmon caught were, for example, about to spawn, underlines Catherine Houssard, analyst at the International Reference Center for the analysis of the cycle of life and sustainable transition (CIRAIG).

Sea-farmed salmon

“The simplest and least expensive way to produce farmed salmon is to raise the fish in a net, in the ocean, close to land,” emphasizes Sylvain Charlebois. This is called sea farming.

The problem with this method is that large concentrations of organic matter (food, excrement) in the same place can cause eutrophication: excess nutrients in the water can unbalance the surrounding ecosystems.

Salmon also live very close together, which can promote the transmission of parasites and diseases, and require the use of antibiotics. And it can happen that some fish escape, and enter into competition with the wild species that live nearby – which can, again, lead to a certain imbalance.

Land-farmed salmon

In land-based farming, salmon are kept in large artificial ponds, which operate in a closed circuit.

The advantage of this method is that the salmon live in a controlled environment and do not disturb the surrounding ecosystems.

But this requires the use of significant resources, and in particular, a large quantity of fresh water and large spaces on earth.

Whether at sea or on land, salmon being predators, their diet is mainly based on meal from other fish, the impact of which must also be taken into account.

Verdict ?

All in all, experts agree that there is no ideal solution. “It’s really not easy to decide,” says Catherine Houssard.

A recent life cycle analysis carried out in 2023 shows that wild salmon would be preferable, when compared to farmed salmon, in terms of greenhouse gas emissions.

“But the problem is that current stocks of wild salmon are not sufficient to meet consumer demand,” underlines Olivier Morissette, recalling in passing that “salmon is, by far, the most consumed fish on a global scale. of Canada.”

The good news is that breeding practices are improving more and more, thus reducing the environmental impact of their production, underlines Sylvain Charlebois.

“Fish raised in Canada, with a diet based on alternative products such as soy or insect proteins, could be a solution for the future,” suggests Catherine Houssard.

In the meantime, it is better, according to her, to avoid fresh salmon transported by plane, to limit the footprint linked to transport and losses. “Frozen smoked salmon remains a better choice than gravlax, which is made with fresh salmon,” she illustrates.

But ultimately, the best solution could be to turn to other fish – such as mackerel or sardines – which give less trouble in terms of environmental impacts.

Read the article “Aquaculture is the likely cause of wild salmon extinction”

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