If you buy a small souvenir totem pole in Vancouver, Canada, it will likely have a salmon at the bottom of the pole, a bear above it, and an eagle or mythical thunderbird at the top. For the First Nations people of the west coast of Canada, the salmon is the basis, the foundation of their world. What harms the salmon destabilises that world. The same may well be true for the whole world.
A continually growing world population with an increased hunger for protein cannot be fed from the land; it has to be fed from the oceans, but the stocks of wild fish have been seriously depleted already. The only real answer, as far as animal protein is concerned, is farmed fish (okay, an alternative is insects), and salmon is a major farmed fish in the western world. So the risks created by salmon farming, the risks actively taken by farmers and by regions that allow them to set up farms in their waters, are also risks to the food security of the population.
Risk 1 – Pollution: fish farms pollute, they produce a lot of waste in one place, so they have to be positioned above strong currents to distribute the waste, nevertheless there is evidence they harm local ecosystems.
Risk 2 – Escapes: fish pens may be damaged and fish escape. The damage may be caused by storms, with climate change they are becoming more frequent and more violent. When the fish escape, it is not just a question of lost livestock; escaping females may breed with wild salmon but their progeny are unlikely to survive long in the wild and so the health of the wild population is weakened (escaping males cannot compete with wild salmon in the breeding stakes). But the full impact of escapes is not known.
Risk 3 – Sea lice: farms are susceptible to sea lice which attack the captive salmon in farms and skin their heads, leading to death by exposure. Up to a quarter of salmon in farms are lost in this way. Farmers may address this by chemicals, but those also kill any prawns or lobster or other crustaceans in the vicinity; bio-controls (smaller fish that will eat the lice off the salmon) mean introducing wild fish into farms with risk of disease, and those fish e.g. wrasse – a grouper-sized fish – are already under threat.
Risk 4 – Feed: salmon are fed on meal which may contain around 14% fish and up to 50% soya. Salmon are carnivores but farms are trying to turn them into vegetarians for economic reasons. If you feed only soya to a salmon it will literally explode. A lot of soya is produced unsustainably and the fish used in the meal is generally harvested unsustainably by factory trawlers.
There are several more risks and issues, these are illustrative.
When a company decides to take risk, it assesses it and sets an appetite. It also sets a tolerance for the risks that go with it. When an eco-system is subject to risk, who sets the appetite and the tolerance?
Data Sources: The Guardian Long Read, 15 Sept 2020 by Mark Kurlansky; The Case for Fish Farming – TED talk by Mike Veling