Author: Luke Leuty
Imagine yourself in a fancy restaurant. Your waiter has just served you drinks and now looks expectantly at you while you browse their menu. Undecided, you are stuck between the filet mignon or the braised salmon. Finally, after what feels like an eternity to your waiter, you order the salmon. Your meal arrives, and you dig in! What you do not realize however, is that you have also dug salmon into a deeper hole. In fact, since the 1960s, wild salmon have faced extreme risk of extinction due to the farming and overharvesting of salmon. Now this may seem a bit of a stretch, but the reality is that there are now only two places where strong populations of wild salmon can be found, Alaska and eastern Russia. Farming salmon not only poses a risk for wild populations, but it is also a hazard to you too!
History of Salmon Farming:
Salmon caught the attention of breeders for three reasons: The first reason is their eggs. Unlike many other fish species, salmon eggs are easily visible due to their neon orange color and size. These eggs are easily collected in order to raise the fry. The second reason is their easy conversion to food. Normally, fish fry have several dieting stages before eating large food pieces like chopped fish. The salmon bypasses these stages, thanks to a large yolk sac the fry feed on for the first few weeks. This allows the fry to almost immediately begin consuming larger pieces of food, making farming a lot easier. The third and final reason is the salmon’s quick adaptation to captivity. Fish often fight borders, attempting to leap over nets and bashing themselves repeatedly against walls. Salmon are rather calm and thus make for an ideal farmed fish.
Salmon farming began in Norway by the Gronvedt brothers. They collected juvenile salmonids and raised them inside nets in the local coastal oceans. It did not take long for people to realize that money could be made by raising salmon, since wild populations had already begun decreasing. Salmon farmer Gjedrem began expanding upon the brothers' work. Eager to increase profits, he began selectively breeding salmon. Through a span of 1.5 decades, Gjedrem took a wild strain of salmon and increased the grow rate two-fold. His work was so significant that scientists have named it a new species, Salmo domesticus. Salmon farming did not stop in Norway. In fact, farming has spread all over the world! Farms all over the world now produce an astounding 3 billion pounds of salmon, per year! It is no surprise then that salmon are listed as the number one finfish in Western fish consumption.
Even though salmon farming may look like it is beneficial, it hurts not only the life of the salmon inside the nets, but also the wild salmon. Much like factory farming in agriculture, salmon are often farmed in conditions where open wounds, disease, and poor water quality plague the salmon. In order to increase profits, farmers fit as many salmon as they can into net pens. This provides a breeding ground for various diseases and parasites, which might not exist or be as prevalent in wild populations. Even though wild and farmed salmon are divided by barriers, these diseases and parasites are not. Oftentimes wild salmon have courses that encounter salmon farms, and these pathogens are transmitted to the wild fish. While diseases in farmed salmon can be addressed, wild populations are left to suffer. Because there is a large number of fish concentrated in one area, waste from these fish is also concentrated. Poor water conditions not only affect the salmon but also native organisms living in that area. It turns a once healthy ecosystem into an ecological sewer.
As if the pathogenic consequences of salmon farming were not bad enough, there is also the risk of escaped fish from these enclosures. Three things can happen when a fish escapes. The first is the fish simply does not survive. The second is the fish outcompetes and replaces the native salmon. The third option is that the fish can integrate itself into the wild fish populations, weakening the genetic pool wild fish come from and eventually causing the extinction of the wild salmon. This third option applies to areas where there are native strains of the farmed species, such as Norway. Even though escaping fish can be rare, when it happens the number of escaped fish is massive. According to Peter Bission, fish escapes often occur in the hundreds of thousands. Washington reported over 500,000 fish escaped over a three year period (1996-99). In Chile, millions of fish are reported to have escaped in only two years(1994-95)! So fish are escaping, but what does that mean for native salmon? Well, in one experimental study, the release of farmed salmon resulted in a steady decline in wild species due to interbreeding (Hinder, et al. 2006). Based on this study, where interbreeding resulted in the decline, it is a high possibility that outcompeting native species will result in a faster, more drastic decline in wild populations.
Risks and Hazards:
The salmon farming industry is one of the leading industries in aquaculture. With over 3 billion pounds of farmed salmon being produced, it dwarfs the harvest rate of wild salmon. Not only that, but selective breeding has led to salmon that grow up to twice as fast as their wild counterparts. It seems hard to see any negatives, especially when people are making money. Once we break down the risks and hazards of farmed salmon, however, we see two problems.
The first risk is the chance of salmon escaping into the wild. While it may not be a direct risk to people, it is a great risk to native wild populations of fish. An invasive species can quickly upset an ecosystem. Not only can the fish itself impact the environment, but it can also bring new diseases. Farmed salmon are no different. In fact, according to one article, “The evidence that ISAV and PRV (diseases affecting both wild and farmed salmon) have spread between widely separated regions of the world elevates the risk to Pacific salmon.” (Morton & Routledge, 2016). The risk is too great to wild species of salmon and can devastate an entire ecosystem.
The second dilemma is the risk of Polychlorinated biphenyl (PCB), in farmed salmon. PCBS are man made chemicals that have been connected to causing cancer, damaging neurological systems, and harming the immune and reproductive systems. As with many chemicals, the higher up the food chain, the more concentrated a chemical becomes in each organism. Because the farmed salmon’s food is composed of smaller fish ground up into fish meal, they receive a significantly higher concentration of PCBs than their wild counterparts. PCBs typically accumulate in the fat of an organism. On average, farmed salmon have roughly 10% more fat than wild salmon, allowing for more buildup of PCBs in farmed salmon. Since salmon is one of the most frequently eaten finfish in the Western world, this hazard has an increased risk of entering your body! PCBs also take a long time to be removed. It can take up to a decade for only half of the PCB in your body to be removed. Wild salmon contain significantly less PCB concentrations as opposed to farmed salmon. This is due to the variety in their diets, as well as less fat percentages.
Salmon farming is a relatively recent industry that brings a once scarce fish to the markets in countless numbers. Farmed salmon outnumbers wild salmon in the markets 3:1. However, farmed salmon is an area of concern. Creating factory farms in the oceans not only creates poor conditions for the farmed salmon but also affects wild salmon. New diseases are brought into an ecosystem with new fish, so farmed salmon can infect wild runs of salmon when introduced. Farmed salmon can also escape their pens and either outcompete or dilute the genetic pool of wild salmon. The salmon themselves can pose a risk to humans. PCBs become concentrated in farmed salmon, making eating them a hazard. Farming salmon is a concern that needs to be addressed both by the government and by the public.
Bisson, Peter A. (2006). Assessment of the Risk of Invasion of National Forest Streams in
the Pacific Northwest by Farmed Atlantic Salmon. USDA.
Greenberg, P. 2011. Four Fish: The future of the last wild food. New York, New York: Penguin
Hindar, Kjetil, Fleming, Ian A, McGinnity, Philip, & Diserud, Ola. (2006). Genetic and
ecological effects of salmon farming on wild salmon: modelling from experimental results. ICES Journal of Marine Science, 63(7), 1234–1247. https://doi.org/10.1016/j.icesjms.2006.04.02
Morton, Alexandra, Routledge, Richard. (2016). Risk and precaution: Salmon farming Marine
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