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.