Image Salmon by Travis S. CC BY-NC 2.0

The Tasmanian salmon farming industry goes to great lengths to convince consumers that their fish are not genetically modified organisms (GMO) [1]. Well.. that's not entirely true. It is factual that the salmon are not transgenic, but it is misleading to imply that their genetics are not heavily manipulated, and with severe and cruel implications for the fish. 

 

Genetic Manipulation of Salmon

There are numerous unanswered questions relating to the weird laboratory manipulations to the genetics of these fish. Farmed salmon in Tasmania are genetically manipulated to be what’s called ‘triploid’. Normally, most animals (including humans) are what is called diploid, meaning that they have two sets of chromosomes, one inherited from the mother and the other from the father. Thus, we have two sets of all genes, and they operate either in tandem or in opposition to each other. Triploid organisms have a mutation that gives them three sets of chromosomes. In this case, three is definitely not better than two. 

 

What exactly is a 'triploid' salmon?

The triploid mutation occurs naturally in salmon on rare occasions. However, in a fact sheet on triploidy in salmon, Huon Aquaculture states that “triploid fish (and other triploid critters) are not genetically-modified organisms (GMOs); rather they are hybrid fish. … In the case of triploids, no genetic material has been engineered. There is simply an extra set of the existing genetic material, causing infertility” [1]. They describe the process of creating triploid fish in the laboratory, by forcing the fertilised eggs to retain an extra chromosome through subjecting them to pressure shock shortly after fertilisation. 

Huon Aquaculture is inaccurate when they say that triploid fish are hybrids. A hybrid is generally interpreted as a cross between two species, for example, a mule that results from the crossing of a donkey with a horse. Triploid salmon are not hybrids between two species, they are artificially induced genetic mutants of a single species. 

While it is accurate to say that the genes of induced triploid salmon have not been spliced with the DNA of other species (”transgenic”), or that they are not engineered to express novel proteins that do not normally exist, it is misleading to say that they are not genetically modified to have biological, physiological, ecological, and genetic differences that make them more different than if they contained a crossed gene or a novel protein. Put it this way: you would not want to be a triploid salmon. 

 

Genetic Torture 

The triploid mutation renders the organism sterile, and its other effects are profound and often harmful to the fish. A third of triploid salmon have deformed vertebrae, compared with only 10 percent of diploids [2]. They often develop lower jaw deformities including jaws that are downward curved, shortened, or misaligned, which affect their performance, welfare and value [3]. They have a high rate of heart deformities that impair their temperature tolerance [4], and all triploid individuals have larger red blood cells to accommodate the extra chromosome, but this compromises their oxygen consumption, making them weaker and more prone to suffocation [5, 6]. Nearly two-thirds of triploids suffer from absence of primary gill filaments, and this reduction in gill surface area is thought to impair their respiration under vigorous exercise or suboptimal environmental conditions [7]. Triploids are also more susceptible to gill disease [1]. And a large percent die before their first feeding [8]. The biological and physiological differences between triploids and diploids is so significant, in fact, that one salmon researcher quite famously asserted that, “The best approach to using triploids in aquaculture may be to consider them as a new species, therefore taking a slower, more cautious approach” [9]. 

 

In the Pursuit of Profit

So if the triploid mutation is so bad for the fish, why do it, you may wonder. Simple: it’s more profitable for producers. Because the fish are sterile, instead of putting their metabolic energy into reproduction, they shunt it toward growth. So they grow faster. Never mind the deformed jaw and spine, never mind the deformed gills and blood cells and difficulty breathing, and never mind the greater susceptibility to disease, it’s more profitable. 

The deformities are so great, however, that in May 2021, the Norwegian salmon mega-producer Norway Royal Salmon announced that they were discontinuing their use of triploidy due to animal welfare concerns [10]. The salmon industry in Tasmania still uses it. 

So to take the broader view, what is it about GMO that we fear? I suspect it has to do with eating something that isn’t what we think it is, that it’s a mutant, a ‘Frankenfish’, perhaps less wholesome. Something that might have genetic differences that might somehow be passed along to us as our bodies assimilate the proteins from these sickened fish into our own essence. If that is why we fear GMO, then triploids should be far more scary to us than simply having a gene from another fish. 

 

REFERENCES

[Click here to go to Triploid References]

With every bite of salmon, we are giving our implicit consent to cruelty