Sunday, July 21, 2013


Frankenfish. For me, the word conjures an image of a child’s drawing of a fish—huge teeth, multi-colored and distorted, coloring outside the lines—a cross between Jaws and Nemo. This is what the news media has lovingly dubbed the genetically engineered (GE) Atlantic salmon, which recently passed (pending public comments) the FDA after nearly 17 years in review. The FDA concluded the fish would have “no significant impact” (e.g. it poses neither significant health or environmental risks). The public comment period is now over, and the AquAdvantage Salmon is now undergoing final review—if it passes, it will be the first GE animal to enter the markets.

The AquAdvantage Salmon (as it’s being marketed by AquaBounty) was developed by scientists at the University of Newfoundland, and adds two genes (a promoter gene from the Ocean Pout and a growth hormone gene from faster-growing Chinook salmon) in order to allow the salmon to produce growth hormone all year long instead of seasonally, thus achieving full size in about half the time of a wild Atlantic salmon.

A genetically-engineered salmon and regular salmon of the same age
The aptly named Ocean Pout
So what are the potential problems concerning GE animals? (I use the term genetically engineered rather than genetically modified, as genetic modification has been going on for hundreds of years, since the Middle Ages when destriers were bred for size to be able to hold knights in armor. Genetic engineering is the more recent practice of directly manipulating an organism’s genome using biotechnology). Obviously, GE animals are a facet of the wide-spread and ongoing ethical debate over GMO foods, but here I will focus on the potential environmental impacts of GE organisms.

Genetic modification in Westeros
One of the major environmental concerns with GE plants (like Monsanto’s pesticide-producing corn) is that insects and weeds will evolve resistance, instigating an evolutionary arms race—‘superweeds’ demand the invention of GE plants with even higher levels of pesticide production, which will in turn breed super-superweeds, etc.. The main concern with GE animals is that if they escape, they will compete and/or interbreed with local populations, with unknown consequences. For salmon, this is already a problem with current hatchery and aquaculture practices, but in this case there is concern that the transgene conferring elevated growth rates will give GE salmon a competitive advantage over wild populations. However, AquaBounty is taking serious measures to ensure that its fish will not interbreed (more below), and the GE salmon will grow faster, but not larger, than wild salmon.

The most recent news flurry about GE Atlantic salmon was sparked by a study from ecologist Peter Westley. A few weeks before this study hit the mainstream news, Westley came and gave a seminar to the UC Santa Cruz Ecology department, presenting the results of his lab studies on potential interspecific hybridization between AquAdvantage salmon and wild brown trout. (An amiable man and good speaker, Westley did a good job of diplomatically presenting the science without expressing his personal opinion on whether GE salmon should enter the market, a challenge for all scientists, especially concerning controversial topics). In his study, he and his colleagues found that under lab conditions, transgenic hybrids (i.e. offspring of a wild brown trout and a GE salmon) outcompeted both GE and wild salmon.1 While this study validates concerns about the potential risks of interbreeding between GE salmon and other closely related species (as well as wild salmon), these studies are necessarily limited to laboratories, making it difficult to know the actual environmental consequences should GE salmon escape.

AquaBounty has devised a triply secure method against the possibility of GE salmon escaping and interbreeding with wild populations: the GE salmon will be sterile, all female, and raised in land-locked pens in Panama (where local water temperatures are inhospitable to the salmon, should they escape). The all-female population will be created using gynogenesis, and sterility will be achieved by making the fish triploid (3 chromosomes) via heat and pressure shock on the eggs.2

Process of AquAdvantage salmon production
(figure from FDA report)
So the question remains, is the risk of putting GE salmon on the market worth taking? Let’s consider the alternative. People LOVE salmon—it’s delicious. So at the heart of this debate, it’s a matter of supply and demand. Our current salmon supply comes from a combination of wild populations, supplemental hatchery production, and farmed salmon. Wild salmon populations are in trouble—and on many rivers, hatchery fish have already interbred with wild fish populations, decreasing their genetic diversity (some rivers, such as the Sacramento in California, would likely not have salmon populations at all anymore if it weren’t for hatchery production). And many large salmon aquaculture operations (the source of farmed fish) raise their fish in net-pens in the ocean (see previous post), making the risk of escape and interbreeding more likely than for AquaBounty’s proposed operation.

At this point, it seems we are stuck trying identify the lesser of several evils. The bigger picture problem is how we are going to feed a growing world population. Fish is a relatively cheap protein source, and GE salmon grow faster than regular farmed salmon on less feed, thereby efficiently creating more marketable fish in a shorter time. Put this way, AquaBounty starts to sound a lot like CAFOs, with the associated problems of crowded conditions, disease, and use of antibiotics… and this is already a problem with current aquaculture operations. In the case of CAFO animals, there are no wild cow or chicken populations that we’re trying to protect by supplying an alternative, but there are movements towards locally sustainable farming (with the associated increases in cost per pound). So regardless of whether it’s traditional aquaculture or GE salmon aquaculture, the conditions under which the fish are raised should be an important consideration for both health-conscious and environmentally-conscious consumers.

1) Krista B. Oke, et al. (2013). “Hybridization between genetically modified Atlantic salmon and wild brown trout reveals novel ecological interactions.” Proceedings of the Royal Society B.

1 comment:

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