Sustainable Salmon Farming: Is it Possible?

Salmon cakes, lox, baked salmon, teriyaki salmon, salmon tacos,  pan-fried salmon, poached salmon, salmon poke bowls—simply put, we love salmon. To match growing demand, now roughly 60-70% salmon comes from farmed, or aquaculture, systems. It’s clear that we need sustainable salmon farming—but is it possible?

Why is Salmon Farming Popular?

While salmon used to be considered a luxury food in many areas of the world, more people are eating more of it. In fact, global salmon consumption is roughly three times as high as it was in 1980! 

Because wild salmon stocks couldn’t possibly meet this tremendous rise in demand, salmon farming operations have stepped in—making it the world’s fastest growing food production system.

While salmon aquaculture has put salmon on more plates around the globe, it also comes with some pretty serious environmental and ethical concerns. 

Environmental Impacts of Salmon Farming

The environmental impacts of salmon farming are varied, and largely depend on the type of aquaculture system used. It’s considered that closed containment salmon farming systems have less of an environmental impact because there’s less risk that salmon will escape or dangerous pollutants will enter the environment.

However, most farmed salmon come from open-net pens, where net-pens or “cages” are in freshwater lakes or coastal areas, which allows for a free exchange between the aquaculture system and the surrounding environment. This means that chemicals and waste can all enter the surrounding water. Salmon can also escape, leading to the spread of disease or parasites. 

Common Salmon Farming Practices that are Not Sustainable

As it stands, there are several farming practices that have a negative impact on our environment. To quote The Guardian, “fish farming currently creates as many problems as it solves.” 

Problematic Practice #1: Open-Net Pens

Open-net pens are the most common aquaculture system for salmon, and they’re also responsible for many problems. As they're directly submerged in bodies of water, they’re likely to contaminate the surrounding environment with waste, antibiotics, or chemicals used in fish farming. 

Additionally, diseases like Piscine orthoreovirus (PRV) can spread to wild fish populations, which are already in trouble. 

Problematic Practice #2: Feed Source

As carnivores with a voracious appetite, salmon requires other animal products to grow. Oftentimes, this requires fish meal that’s been made from wild fish—which are sometimes overfished themselves. 

Not only does this devastate wild fish populations (and other species that depend on them in the food chain), but it also takes away food that humans could eat directly. 

Problematic Practice #3: Confined Conditions

While fish generally prefer moving together in a group, some aquaculture systems have hundreds of thousands of salmon packed tightly together. This can, and does, give rise to the spread of parasites and disease, and also contributes to growing concerns about sea lice. 

Lepeophtheirus salmonis, commonly known as sea lice, feed on fishes’ skin and blood. Over time, they’ve taken a particular interest in salmon, and have even adapted to live directly on them. In confined salmon farming operations, infestations can spread quickly, meaning that infected fish cannot be sold, and instead must be discarded—possibly infecting wild species, too.   

Problematic Practice #4: Large Operations Required to Survive

Just like with other forms of animal agriculture, we’re seeing a shift towards larger salmon farming operations. When fish farming started in countries like Norway, a single pen was licenced and practices weren’t as detrimental for the environment. 

Now, most farms have eight or even 10 pens—accounting for the same number of fish as the entire wild Atlantic salmon population! We’re also seeing an increasing trend towards salmon farms being owned by fewer and fewer large multinational companies. In Scotland, for example, just five companies account for 96% of salmon production.

Who Supports Salmon Farming?

Who supports salmon farming—and is there even a reason to? While salmon farming is associated with significant concerns, there are two main reasons to support salmon farming: it creates jobs and it provides food to meet growing levels of salmon farming consumption. Let’s take a look at both of these benefits.

Job Creation

In British Columbia, salmon farming provides more than 7,000 jobs for people living in coastal regions, and provides $1.5 billion every year for the economy. In Canada, as well as Chile, Norway, and Scotland—where 96% of the world’s farmed salmon are produced—there’s no doubt that communities are supported by the livelihood opportunities that come about with salmon farming. 

Unfortunately, they often bear the burden of economic, social, and environmental costs, too.

It’s been reported that the negative impacts of salmon farming—environmental and social consequences total around $50 billion in losses. Transparency and accountability are low, and the cost of salmon mortality, disease spread, feed impacts, and pollution are high.  

Feeding Our Growing Population

It’s predicted that by 2050, our global population will reach 9.7 billion people. Because of that, our demand for food will rise by 50%. Aquaculture will be a significant source of the world’s protein, especially because many wild fish reserves are on the brink of over-exploitation. 

However, in order to meet demand sustainably, there need to be some significant changes to salmon farming systems so that they minimize environmental impact.  

Some Ways to Create a Sustainable Salmon Farming System

As we previously mentioned, closed containment farming methods mean that pollution and escaped fish can’t negatively impact the surrounding environment. There are two main ways this can be accomplished, and one of them is increasingly being used to farm salmon. 

A re-circulation system is a type of closed aquaculture that, as the name suggests, treats and re-circulates the water in the system. By treating the effluent, waste and pollutants are removed, meaning that pollution and disease transfer are less likely to enter natural bodies of water. 

Sometimes, a re-circulation system is used on land, and the discharged water and solid waste can be used to grow plants or as a fertilizer. Even the CO2 that’s been produced by the salmon can be used to grow plants! 

While land-based re-circulation systems are considered to be “the most promising technology to grow the industry,” it does require a significant level of water, land, and energy. Also, while solid waste and water discharges can be used sustainably, it has yet to be seen that that actually happens. 

As one of the most environmentally impactful aspects of salmon farming, feed that comes from wild fishmeal and fish oil is required for salmon raised in re-circulation systems—which also jeopardizes its ability to be a sustainable farming system. Even when plant-based feed is used instead, it has a similar environmental impact.  

So, while land-based re-circulation aquaculture systems have the potential to be used as a sustainable salmon farming system, many improvements still need to be made to allow it to win the farm raised vs wild caught salmon debate. 

Summary: Is Sustainable Salmon Farming Possible?

It’s clear that our growing appetite for salmon has to be met in some way—and unfortunately wild salmon populations aren’t big enough to supply. That said, however, salmon farming has a long way to come before it can be considered sustainable. 

If you, like these magical fish, have a voracious appetite, we’d recommend cutting down on your consumption of farmed salmon, and choose more sustainable wild caught salmon instead.