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Posted by on Apr 25, 2013 in Evironment, Genetics, Life, Skepticism, Technology | 1 comment

Genetically Modified Salmon

The FDA is reviewing the so-called “Frankenfish” again.  Once again, we see thousands if not millions of people who are yelling about something that they obviously don’t understand.  It’s really depressing that people ignore science when it doesn’t say what they want it to say.

So, let’s take a minute to take a look at this fish and what science, not instinct tells us.

Basically, the genetically modified is an Atlantic salmon (Salmo salar) that has two additional genes.  The first is a gene from the Chinook salmon (Oncorhynchus tshawytscha) that regulates the salmon growth hormone.  The second gene is from an ocean pout (Zoarces americanus) that is a promoter gene.

The promoter gene’s sole function is to regulate the growth hormone gene.  It does not produce proteins or anything else.  It is merely present.  Why an ocean pout gene?  Because it does one thing that the salmon promoter doesn’t do.  It functions year round.  The salmon promoter gene is only active during the spring and summer.  Since this gene regulates the growth hormone gene, the salmon only grows during the spring and summer.

So, the entire process here is to take a salmon gene and another gene that doesn’t produce any proteins and make a fish that grows twice as fast.  Meaning it reaches salable size in 18 months rather than three years.

But wait, apparently part of the reason that this offends people is because it’s not natural.  Making fish grow twice as fast isn’t good.  Except that almost all aquacultured salmon grow to maturity in 18 months.

Salmobreed, a salmon stock company, has developed salmon that grow almost as quickly (18 months or so, to salable size).  They have done this using that ancient technology of artificial selection.  They just found fish that grew fast and mated them to other fish that grew fast and continued to do so for several generations.

I’d be willing to bet that if we examined the promoter gene in SalmoBreed fish (which I’m sure they won’t let anyone, being a company and all) that the promoter gene would look almost exactly like the promoter gene from the ocean pout.

OK, well what about this ‘aquaculture’ thing?  People should only eat wild fish or fish farming isn’t good.

Here’s the deal.  Over 80% of all salmon produced for human consumption is already farmed.  And (apparently) a big chunk of that is the SalmoBreed (or equivalent) fish.  Just under 70% of other salmon species are also aquacultured.

Fish farming, aquaculture, is about the only way we can sustainably feed fish to the planet.  Without aquaculture the prices of seafood would be very, very high.  Ten years ago, aquaculture provided one-third of all seafood.  In 2011, 80 million tons of seafood was provided by aquaculture.  Over 90% of the shrimp in the US are aquacultured.

What about being released into the wild?  Genetically modified fish could wreak havoc on the ecosystem.

Well, except for the fact that GM salmon are only going to be used in land based tank farms (pg54), the males of this species are less reproductively successful than wild type fish (and here), and the GM fish are slower and less efficient at swimming and recovery after stress, then sure it’s theoretically possible.

Even if they did get out though, so what?  Salmon have a very specific mating pattern.  The fish swim from the ocean to the river in which they were raised, spawn, then die.  The GM salmon do not have a spawn point, so they have no place that they can swim back to.  I imagine this great big, but slow fish looking around wondering where everyone has gone?

So, there’s very little chance of the GM fish escaping and even if they did, there’s no chance that they would singly handedly destroy the ecosystem… certainly no more than humans have already screwed it up by daming spawning rivers and catching 80% of the fish as they swim upstream.  (Ecosystem pro-tip: Capture fish AFTER they lay eggs, not before).

Further, these fish will only be raised in freshwater environments, not saltwater.  So, even if they did somehow ‘escape’, they wouldn’t be able to survive in the oceans.  Not to mention that they would have about three days to learn to forage in the ocean instead of be fed fish pellets every morning at 11am (or whatever).

Now a few people that I know will be saying that they only eat wild caught salmon and that it’s the only fish to eat.  And that’s fine.  You want to pay for true wild-caught salmon.  Fine, go for it.  But don’t talk to me about protecting the environment and the salmon ecology.  Wild caught salmon is not sustainable, it cannot feed everyone, and humans are out-competing other organisms who really could use that food source (bears, raptors, etc).

Finally, a point about taste.  I’ve never eaten true, wild-caught salmon.  I’m OK with what I do eat.  It tastes just fine with a little herb butter.  Maybe true, wild-caught salmon is way better.  Great.

But, I’m willing to bet that most people will not be able to tell the difference between the GM fish and the selected for fast growth fish and non-modified aquacultured fish.  Indeed, I’d be willing to put money on even experts not being able to tell the difference between wild-caught salmon and any of the three aquacultured salmon.  You see, it’s salmon.  It’s all the same fish.

The GM fish uses a salmon gene to produce salmon proteins which cause salmon muscles to continue to grow year round.  The selected for fast growth fish uses salmon genes to produce salmon proteins which causes salmon muscles to continue  to grow year round.  The other fish use salmon genes to produce salmon proteins which causes salmon muscles to grow, 6 months out of the year.

That’s the whole difference.  That’s all.

Now, why are we having this discussion again?

 

 

  • BioGrad

    A few things: (1) a promoter is not a gene itself. It’s a regulatory sequence. Please wikipedia this for a further explanation. (2) To describe traditional breeding as an “ancient technology” is true, but carries a connotation of the technology being inferior. It is not necessarily, but it is certainly less directed than GE. (3) To say that one promoter likely looks the same as another promoter based upon whether we observe a similar phenotype between two fish is highly speculative, to say the least. There could be a very large number of ways to explain how we achieve two fish — one GE, one traditionally bred — with similar growth time phenotypes. I would venture to say there are a combination of genes that on net are acting to define the phenotype of the traditionally bred fish due to so many genes being moved with traditional breeding, where as know who is responsible for the GE salmon. Overall, however, I appreciate your references and am generally receptive to your argument.