A fine kettle of fish fearmongering

posted in: Science & Society | 8

Consumers continue to demand fish at very high levels, and this puts pressure on wild fish stocks. A report recently highlighted the fact that aquaculture is becoming increasingly important:

If we continue to fish at the current pace, some scientists predict we’ll be facing oceans devoid of edible marine creatures by 2050.

Aquaculture could come to the rescue. The Food and Agriculture Organization of the United Nations predicts that farmed fish will soon surpass wild-caught; by 2030, aquaculture may produce more than 60 percent of fish we consume as food.

There are several ways GMOs could help keep us from overfishing while still supplying sufficient resources to salmon-eating humans and their pets. One company is using GMO yeast to feed salmon. Another effort is being undertaken to have plants provide the necessary oils for the fish. Both of these strategies help to reduce the need for smaller feeder fish for the salmon. Another way to reduce the resources required for fish farming is to have the fish grow faster. They convert feed faster, and don’t need to be in tanks or pens for as long a period of time. This could be from conventional breeding [PDF], or it could be from GMO fish, as AquaBounty has done. And the AquaBounty strategy also includes having the fish grown only in inland recirculated tank systems–which the Monterey Bay Seafood Watch team has scored as a “Best Choice” for other salmons.

BBC "Trojan gene" storyFor many years now, we’ve been awaiting the approval of the fast-growing GMO salmon. Of course, the idea of fast-growing fish has ignited fears over the years, and a great deal of ink (or electrons) have been spilled by many of the fearful. (Although I once asked this author if there was evidence of that Norwegian fast-growing salmon causing problems. I think his response means no, he has no evidence.)

Many activists cite the work of William Muir and Richard Howard, who published a research paper about the potential for some fish to become “Trojan fish” which could out-compete fish without a size advantage. The BBC covered this work in 1999, as shown in the accompanying image.

From the beginning, Muir tried to tell people that these results should be interpreted narrowly:

Muir also cautions that the results of his laboratory study should be interpreted conservatively. “The study does confirm there are significant risks to natural animal populations associated with the release of transgenic animals. We assumed a consistent environment with only one variable – sexual preference for size coupled with low life expectancy for the transgenic. The natural world is not nearly as orderly, and genetic background changes could negate the Trojan gene,” he says.

The work involved a gene that offered a mating advantage–the oversized adult growth of the fish under investigation made them popular, it seems. But–not all traits will result in the same outcome. And Muir has been trying to tell this to the activists who have been mis-using this work for all their anti-GMO claims for a long time. A recent example was here: Foes of GE salmon raise specter of ‘Trojan gene’ effect.

Not so, says the author of the Trojan Gene hypothesis, William Muir, an animal science professor at Purdue who has been yelling loudly, to little effect so far, that his work is being misrepresented by the GE salmon’s opponents.

Muir said the assumption at the time of the study in 1999 was that a GE salmon would grow faster and bigger and that its size would be an unbeatable advantage in mating.

But AquaBounty salmon don’t get any bigger than ordinary salmon, they just reach full size faster, so any size advantage they have is temporary.

More importantly, Muir said that studies show that transgenic salmon are lousy at the courtship required for mating.

Of course, the fact that Muir supports the idea that the risk of harm from the GMO salmon is low doesn’t daunt folks opposed to it. Funny how they cling to his initial work, but not what he says about the salmon that doesn’t suit their narrative.

Kettle of GMO FishMuir has continued to study the behaviors of GMO fish. Recently he and his team have produced another paper on the subject. They looked at Glofish®, which have been feared by activists of resulting in the Trojan behavior. This controversy was re-ignited a while back, as you can see from the coverage the glowing aquarium fish got from a number of outlets. Biofortified attempted to put out the flames at that time. Other outlets? Not so much. Threat. Threatens. Worries.

So thousands of shares, propagations, forum posts and comments later–people have the got the fear meme in their heads. But what was the outcome of the new work? Evolution in action: Mate competition weeds out GM fish from population.

Purdue University research found that wild-type zebrafish consistently beat out genetically modified Glofish in competition for female mates, an advantage that led to the disappearance of the transgene from the fish population over time.

Well, that’s data. And their previous model? “The study also showed the effectiveness of a model Muir developed to assess the potential risk posed to natural populations by transgenic organisms. ” Environmental activists should be comforted by the effectiveness of this model, right? They seem comfortable with the ideas and predictions of climate models.

But how did this play out in the media? How much coverage did we see on this important follow-up to the previous fears?

Um. Well, not so much. I’ve been looking, and so far only two media outlets have done the right thing in attempting to un-scare everyone. One piece from Brooks Hays with UPI: Genetically modified fish outcompeted in evolution experiment. Commenters complain about this as evidence of evolution. Heh.

wapo_glofish_2015Congrats to Chelsea Harvey and the Washington Post for being the first ones to cover this work in real depth, with much more than just the press release but other important context: No, genetically modified pet fish are not going to wreak ecological havoc. And this part–where she quotes Muir–is quite nice:

And when it comes to GMOs, looking at these kinds of evolutionary outcomes can be an effective way of approaching conversations about their safety and their environmental risks, according to Muir. “This is such a heated and charged argument and so filled with emotion that as a scientist you say, ‘Let the data speak for itself,’ ” he says.

But does the data speak for itself? The fear was pretty chatty–but the data? It’s been pretty quiet. There’s only one comment at the WaPo piece, and it was mine. But some people don’t think that evidence from evolutionary outcomes is sufficient, as we’ve seen for the recent data from sweet potato sequencing. But in the long run, it will be the data that matters. And it matters to regulators too. If we want to reduce pressures on wild fish, and reduce resources needed to feed fish fans, let’s look to the data instead of the fear.

Muir, W., & Howard, R. (1999). Possible ecological risks of transgenic organism release when transgenes affect mating success: Sexual selection and the Trojan gene hypothesis Proceedings of the National Academy of Sciences, 96 (24), 13853-13856 DOI: 10.1073/pnas.96.24.13853

Howard, R., Rohrer, K., Liu, Y., & Muir, W. (2015). Mate competition and evolutionary outcomes in genetically modified zebrafish (Danio rerio) Evolution, 69 (5), 1143-1157 DOI: 10.1111/evo.12662

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Mary Mangan PhD is a genomics scientist, with credentials in microbiology, immunology, plant cell biology, and mammalian cell, developmental, and molecular biology. All comments here are my own, and do not represent my company or any other company.