Genetically Modified "GM" Salmon Raised In Self-Contained Systems: Much More Likely To Be Part of a Solution and Not a Problem

A New York Times article (Pollack 2010) appeared on Tuesday, September 21, 2010,   and discussed whether or not specially genetically engineered farmed salmon might be approved for sale in the US. There were representatives of the aquaculture industry and of the firm pushing the idea, AquaBounty  Technologies, speaking in support before an FDA panel, and a number of special environmentalist or consumer’s groups going on record as against the idea in general, or some particular aspect that they felt was underexplored or held potential danger. 

The critics brought up a number of issues that  were treated as being so important of themselves, that the approval process should be delayed or cancelled altogether. But such a single-issue-based disapproval  sometimes overlooked other factors and realities of  salmon ecology,  economics,  and even human medicine, when a more holistic and  interdisciplinary view of the risks and benefits of this AquAdvanatge™  salmon and its method of being aquacultured might be more revealing.

What’s the big deal with salmon?

Salmon now leads in US sales of all fresh, refrigerator case finfish in supermarkets and is the third most consumed seafood product just behind frozen shrimp and canned tuna (National Fisheries Institute 2009). It’s considered to be particularly good for you. It is nationally promoted, responsibly endorsed,  and widely perceived as having health benefits, especially its polyunsaturated fats and omega-3 fatty acid content (Harel et al 2001, Horrocks & Yeo 1999) that outweigh  its risks from mercury for most categories of consumers (Foran et al 2005, Smith & Guentzel 2010). Demand is expected to grow in the restaurant and institutional food service trade not the least because salmon is one of the most popular types of sushi and sashimi  among both high school (FoodServiceDirector 2010) and college age  consumers (Boss 2009).

Why do they farm salmon anyway? Can’t we just catch more wild salmon in the ocean?

Atlantic salmon are still caught in the wild, but their reproductive carrying capacity has long ago been reached, and Atlantic salmon fisheries have basically harvested (and often polluted) themselves out of business in many locales, including most of New England, formerly a rich salmon fishing area. Indeed most wild Atlantic salmon served in the US has been imported from Canada, the UK, or Scandinavian countries, but even so, catches have been declining: In 1996 we imported 566 tons of wild caught salmon, but by 2008 that amount was down to 58 tons.

It should be noted that while the Alaskan wild salmon fishery ----involving a number of different salmon species but not the Atlantic salmon----remains reasonably healthy, the other West coast native salmon fisheries running from Northern California through to British Columbia, have been in severe decline owing to overfishing and environmental calamities, and thus will not provide a ready, sustainable alternative in the future (US Fish & Wildlife Service 2010). The only realistic  alternative source for a growing demand for salmon is to use aquacultured salmon.

Can’t we just stock the rivers with more salmon from salmon hatcheries, and let them grow up in the wild in the ocean and have them return to the rivers where we stocked them, just like wild salmon do?

This is being done in Alaska and Northern Europe with some success (and in the Great Lakes although the population cannot reproduce there)  but there are still problems: The stocked fish generally behave like escaped farmed fish and sometimes out-compete the wild fish, and it is not always clear that wild and stocked fish interbreed  successfully, even though they are of the same species. This means that it is sometimes possible to end up, not with an overall increase in the total number of available salmon, but rather the displacement of one type of salmon by another without any net gain in salmon supply.  (Crozier 1993, Erkinaro et al 2010, Skaala,  Glover &  V. Wennevik  2006, Soto, Jara & Moreno 2006,  Uusitalo, Kuikka & Romakkaniemi 2005).

 

 Why do they want to genetically engineer a naturally perfectly good fish in the first place?

The principal reason is that these fish, when farmed, grow to harvest size in about half the time as non-genetically-engineered farm-raised salmon, and that this quick turnaround time means that they can be economically grown in closed aquatic systems, meaning not in pens in the open ocean or nearby brackish waters, but rather in clean artificial ponds  much like modern American catfish farming, ponds or tanks which do not connect to rivers or the ocean. As seen in the catfish farming industry (Stankus 2010), many more variables regarding fish wholesomeness and taste,  water quality, the presence of parasites and diseases, the management of waste products, are much more controllable, although realistically never perfectly controllable, in such closed systems. Salmon farming in a closed system represents a serious incremental improvement in the food safety, economics and as we will see shortly, in the environmental impact of salmon aquaculture.  Genetically modified salmon raised in closed systems will go a long way to exploding the simplistic folkloric natural foods ideology  that Norwegian fisheries researcher  Oivind Bergh (2007) calls the dual myth: That wild fish are always healthier (and therefore always better for you) and that farmed fish are always unhealthy (and therefore always worse for you).  

How do these genetically modified salmon grow so fast?

Basically, two genes have been inserted into their genomes. One gene simply enables internal growth hormone production year round despite the cold (salmon ordinarily stop making growth hormone in cold weather and therefore stop growing during winter months). The second gene basically enables the first gene to activate and do its work.

Most importantly, no hormones that are not native to fish are introduced to this  fish, nor are they fed hormones in their rations. There is no reasonable scientific basis for suggesting that these fish are somehow hormonally disruptive of humans or other animals that might eat them, or even that the enhanced growth hormone production, is damaging to the fish themselves, the arguments used against hormones given to livestock and dairy cows through feed or direct injection.

Why can’t we just wait for the traditional growing out period of non-genetically engineered salmon farmed in bays and estuaries?

There are at least three reasons that make quicker growing farmed salmon, grown in closed systems, a better idea than farmed non-genetically modified  salmon raised in sea pens.

The first is ironically ecological or environmental: Salmon farmed in the traditional manner in pens in bays and estuaries tend to become infested with sea lice, which, while not known to be harmful to humans, stunt the growth and well-being of the salmon being farmed. Unfortunately, once the sea lice find themselves a fertile home base, such as the trapped farmed salmon, they spread, not only to nearby wild salmon, but to other fish species as well, sometimes decimating their number(Costello 2009, Frazer 2009).

The second is also ecological and environmental: The sea floor beneath and areas surrounding sea pens are typically fouled with fecal products, uneaten food, and trace chemicals used to keep the cages from becoming coated with barnacles,  weeds, and the like. Perversely, the increased organic matter in the waters near the cages actually decreases the oxygen levels in the water as well as  the number of toxic compounds in the immediate area by binding with agents that would otherwise remain in solution and generally in a diluted state (Musclow 2005, Mayor et al 2010). See the following for more details.

The third reason is also environmental but includes some clinical implications as well: Quicker growing fish raised in closed aquatic systems with closely monitored water quality show demonstrably lower rates of bioaccumulation of environmental toxins including heavy metals, runoff fertilizer compounds, and especially trace pharmaceuticals like antibiotics used to suppress assorted bacterial and fungal infections in salmon penned up in bays and estuaries (Burridge 2010, Cabello 2006, Fortt, Cabello & Buschman  2007). These materials are not only generally bad for the sea life around them, but, should they accumulate within human consumers, poisonous and potential enablers of diminished antibiotic effectiveness, as they encourage the proliferation of drug resistant bacteria in the environment (Herwig, Gray & Weston 1997).  

What will happen to wild salmon if these genetically engineered fish somehow escape their closed systems and mate with natural salmon populations?

First, at least as currently planned in terms of their major sites of production, the salmon will be raised in places where even the nearest sea and river waterways are seriously unfavorable to them, so it is likely that they would die out because they were in such unsupportable circumstances.

Second, all of these fish are females,  and by design, about  five out of every six are demonstrably sterile. Such a sex ratio and high rate of infertility does not bode well for them to be able to establish a viable invasive population which can compete with local, native fish. (Which generally do not include members of the salmonid family with which they could conceivably try to mate.)

What about possible allergic reactions?

It is unfortunately true that there are a great many people allergic, and sometimes severely so, to proteins in seafood, including proteins in Atlantic salmon (Pitsios et al 2010). However, there is as yet no evidence that the two genes that have been inserted into these AquaAdvantage Atlantic salmon will cause the production of any proteins that are not already likely to be in any other type of Atlantic salmon. A safe and sensible recommendation  would be for people who are known to be allergic to Atlantic salmon not to eat any Atlantic salmon, AquAdvantage type or not, and for the rest of us to eat available Atlantic salmon including AquAdvantage salmon when we want to, because we like it and it is a generally healthy food.

Shouldn’t there be warning labels on such salmon?

Given that there are no known differences in the food safety or nutritional value of these salmon, there is no scientific justification for putting any kind of warning label on them. It might be fair to consumers who, for whatever reason, prefer wild-caught salmon or farmed salmon, to have the salmon labeled simply as wild-caught or farm raised salmon, and mention the country of origin.  This is pretty much the standard procedure in most supermarkets anyway, and as noted below, seems to have little effect on sales. People buy what looks good to them at the lowest price they can get.

Are there any foreseeable disadvantages to genetically modified salmon of this type raised by this method?

Overexpectation, too much “hype” in terms of  certain ecological and economic impacts  is about the only forseeable problem.

At least three pre-existing dilemmas will likely persist despite the adoption of this genetically modified salmon and its method of being raised, but these dilemmas  would also continue without them.

1. Detrimental impact on the global population of small fish and supply of fish byproducts. While all the science thus far suggests that with proper care, these fish can be raised safely within closed systems with virtually no risk to the local fish population by direct invasion of their waterways  and competition for food within them, problems remain with the need of all carnivorous fish (and this includes salmon, farmed or wild) for smaller forage fish, usually caught in the wild to be turned into fish meal for the pellets fed to the salmon, and this can cause population declines in fish that would feed other fish in the wild or feed humans (think anchovies and sardines, for example) directly (Aubin et al 2009, Ayer et al 2009, Mullon et al 2009, Pelletier et al 2009).

 

2. This new type of salmon and way of producing it will not likely produce a great many more jobs in the poorer countries that host these or any other modern aquaculture operations. Unemployment in the poorer countries where this type of aquacultured salmon (and any other type of aquacultured salmon) will not dramatically decrease, because operations such as these are  much efficient in their  use of manpower, particularly when compared to  the still large numbers of increasingly impoverished local traditional fisherfolk attempting to land ever diminishing catches.  This is not to say that the fewer workers in modern farmed fishing would not, in the long run, be better off, particularly if there was a requirement that these international aquaculture companies hire and train displaced local fisherfolk, instead of bringing in alien crews for permanent operations  (Adeel & Safriel 2008, Grigorakis et al 2010 ).

 

3. This new type of salmon and way of producing it will not likely increase the availability of low-cost, high-quality protein in the poorer countries that host these and any other modern aquaculture operations. Barring “set-aside-some for domestic use”  legislation in the countries in which these operations are set up, the local population will  probably not have greatly increased access to cheap salmon for their own consumption. The overwhelming share of farmed (and wild caught) salmon is sold on the international market as a cash crop to wealthy, highly developed countries like the US, and their consumers tend to buy the lowest priced salmon of comparable quality and freshness, regardless of which country was the source (Wozniak 2010).

 

Tony Stankus FSLA [email protected] Life Sciences Librarian, Science Coordinator & Professor

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