Faculty of Science

Aquaculture (Fish Farming): Myths and Reality

Common concerns about aquaculture and the role of science in mitigating them

By Drs. Bryan Neff & Shawn Garner

Dr. Bryan Neff

Dr. Bryan Neff

Humans have a long history of eating fish, at least 40,000 years based on archaeological evidence. Since that time, fish consumption has grown to support a massive food industry, which is globally worth more than 200 billion dollars a year. But where do all these fish come from?

Dr. Shawn Garner

Dr. Shawn Garner

Within the last year, the answer to this question has changed for the first time in history. It is now more likely that a fish was produced by aquaculture (fish farming) than captured in a fishery. This change has been the result of a long-term plateau in fisheries yields, combined with substantial growth in aquaculture yields. However, despite this apparent success, unfounded issues associated with fish farming limit consumer confidence to adopt an aquaculture-supported diet.

Common Questions

Even after more than a decade of aquaculture research, almost invariably the first question asked is: are farmed salmon safe to eat?

Myth: Farmed salmon contain dangerously high amounts of organic contaminants.

Salmon Farm

The Yellow Island Aquaculture Limited Salmon Farm

Reality:  This concern can largely be traced to a 2004 study that showed farmed salmon contain more organic contaminants than their wild counterparts. Its recommendation? Farmed salmon should not be eaten by pregnant women, or really by anyone else. Although sensational and widely reported, this claim cannot be scientifically supported. The miniscule risks associated with eating farmed salmon are outweighed more than a thousand fold by the health benefits of eating these fish. Interestingly, current research on aquaculture diets has the potential to eliminate even these small risks. Contaminants in farmed salmon typically come from the wild fish they eat, so decreasing the amount of fish in their diet would also reduce the contaminants they ingest. Researchers have made progress in this area, using plant products to partially replace fish meal and fish oil in salmon diets. The ultimate goal of a fully vegetarian salmon remains elusive, but even in its absence farmed salmon is exceptionally safe to eat.

Perhaps the second most common question is: are farmed salmon less healthy than their wild counterparts?

Myth: Farmed fish are not as healthy because they get their flesh colour from the addition of an artificial dye.

Reality: This concern is simply unfounded. Farmed salmon get their flesh colour from carotenoids in their diet, exactly the same as their wild counterparts. Carotenoids are pigments produced by many plants, such as the beta carotene that gives carrots their distinctive colour, and which provide many health benefits to animals that consume them. Indeed, red and orange displays are common in the animal kingdom because they allow an individual to show off its ability to obtain these valuable carotenoid pigments. The addition of natural carotenoids to salmon feed thus ensures a nutritionally balanced diet for the fish, and a healthy food for the people who eat those fish.

Another common concern about farmed fish is the danger associated with genetically modified organisms (GMOs), called “Frankenfish” by their detractors.

Myth:  Many farmed salmon have been genetically modified, and these fish expose consumers and environments to serious unknown risks.

Bringing in the catch of the day

Bringing in the catch of the day

Reality: These concerns generally center on the rapidly growing GMO salmon produced by Aquabounty, a small company from Prince Edward Island. Like all GMO animals, these fish have not been approved for sale, so any concerns about GMO salmon are premature. More significantly, any risk from eating these fish would be negligible, as they differ from other salmon only in the addition of two well-understood genes from other fishes, and considerable experimental evidence indicates that they are as safe as conventional salmon.

Much has also been said about the risk of escape and invasion of natural habitats, but GMO salmon would be contained by multiple redundancy, using closed, land-based facilities to rear sterile, all-female fish. Ironically, GMO fish would thus have even less chance of affecting wild salmon than existing salmon aquaculture in ocean-based net pens. Genetic modification offers tremendous potential in aquaculture, and with the proper safeguards, may be key to achieving major advances such as the development of a nutritious, environmentally friendly, vegetarian salmon.

Despite consumer concerns, aquaculture has shown itself to be resilient and a major contributor to the modern food supply. Capture fisheries have been fully exploited for 20 years, so meeting the growing seafood demands of an increasing global population can ultimately occur only through aquaculture. With a wealth of water resources and scientific innovation, Canada is now poised to be a world leader in this area.