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Gm Salmon Out-Compete Natives For Spawning Sites


Tim Smith

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From the American Fisheries Society newsfeed:

Another topic that had been of interest here before.

First Study into Reproduction of GM Atlantic Salmon Reveals Danger of Escape to Wild Gene Pool

If genetically modified Atlantic salmon were to escape from captivity they could succeed in breeding and passing their genes into the wild, Canadian researchers have found. Their research, published in Evolutionary Applications, explores the potential reproductive implications of GM salmon as they are considered for commercial farming.

“The use of growth-enhancing transgenic technologies has long been of interest to the aquaculture industry and now genetically modified Atlantic salmon is one of the first species to be considered for commercial farming. Yet, little is known about the potential impact on wild salmon populations if the GM species were to escape captivity,” said lead author Darek Moreau from the Memorial University of Newfoundland, Canada.

One of the key concerns about a transgene escape is the “Trojan gene effect”, caused when a GM fish outcompetes or reproduces equally against wild rivals, however if the resulting offspring are genetically inferior this could lead a species towards eventual extinction. Until now there is no empirical research to demonstrate the ability of transgenic Atlantic salmon to breed naturally and infiltrate the wild gene pool.

In the wild, reproducing males present two main forms of rivals which any escaping transgenic male would have to compete with; large males which have migrated and returned from the sea and smaller male parr which have matured in freshwater. The large males are aggressive and develop attributes to fight off their rivals, while the smaller male parr use cryptic colouring and ‘sneak fertilisation’ to compete.

To measure the ability of transgenic males to complete with wild males during the reproductive season the team monitored breeding behaviour in a naturalised laboratory setting and used genetic analysis to determine the success of competing individuals at producing offspring.

Large, migratory wild males outperformed their captivity-reared transgenic counterparts in terms of a variety of spawning behaviours. Moreover, despite being less aggressive, non-transgenic male parr were also able to outperform their GM rivals in terms of spawning behaviour, and as a result, achieved higher overall fertilisation success.

“While the transgenic males displayed reduced breeding performance relative to their non-transgenic rivals they still demonstrated the ability to successfully participate in natural spawning events and thus have the potential to contribute modified genes to wild populations,” said Moreau.

While the study provides an estimate of breeding performance under only a single set of physical and demographic environmental conditions, it does mimic a likely invasion scenario where the genetic background of the transgenic population differs from that of the wild population.

“Our study provides the first empirical observations on the natural reproductive capacities of growth hormone transgenic Atlantic salmon,” concluded Moreau. “While the resulting ecological and genetic effects of a transgene escape remain uncertain, these data highlight the importance of preventing reproductively-viable GM salmon from entering natural systems.”

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Except the article explicitly says that DON'T OUT-COMPETE NATIVE OR PARR. Am I missing something??? I think the downside is that they take part in the mating process, but the silver lining is they don't out-compete.

Still plenty of issues to work through before too many risks are taken.

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Except the article explicitly says that DON'T OUT-COMPETE NATIVE OR PARR. Am I missing something??? I think the downside is that they take part in the mating process, but the silver lining is they don't out-compete.

Still plenty of issues to work through before too many risks are taken.

The core finding is here I think...

Until now there is no empirical research to demonstrate the ability of transgenic Atlantic salmon to breed naturally and infiltrate the wild gene pool.

Another part you may be overlooking is that this also opens the door wider to the worrisome "trojan gene" risk.

If adult GM fish compete effectively for spawning sites, but their young don't compete well later, that means the reproductive potential of the spawning site and the females that spawn there are diminished. Remember, one fear about these GM fish is that because they have this increased capacity for growth, they won't compete well when resources are limiting. Less "greedy" fish will have a higher capacity to survive. Earlier studies have been somewhat inconclusive about that effect.

This study establishes that if fertile GM fish get to the spawning sites they will almost certainly reproduce and their funky "don't ever stop growing" genes will proliferate.

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The article is full of "ifs" and "maybes". Alarmist scare tactics promoted by the commercial fishing industry to elimate competition from farmed salmon. The greatest danger wild fish face is overfishing by industrial fishing methods. Fish populations are being wiped out and have been wiped out by commercial overfishing, that's a far greater danger, than the unlikely scenario of farmed fish escaping and successfully breeding in the wild.

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The article is full of "ifs" and "maybes". Alarmist scare tactics promoted by the commercial fishing industry to elimate competition from farmed salmon. The greatest danger wild fish face is overfishing by industrial fishing methods. Fish populations are being wiped out and have been wiped out by commercial overfishing, that's a far greater danger, than the unlikely scenario of farmed fish escaping and successfully breeding in the wild.

Reforming and guiding aquaculture practice toward sustainable practices make a lot of sense. That's one of the things I do for a job.

But reconstruction the genes of animals that will inevitably escape into the wild is a something that we've never done before. There's no choice but to speculate about what it will do because it has never happened before in the wild. There are precedents in invasion biology that raise a lot of red flags.

...we know what kinds of serious problems we get from the natural escapes from aquaculture (Asian carp anyone?). "Scare tactic? How about "prudent caution"?

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What I'd really like to know is the real success rate of induced polyploidy. What safety measures are in place to make sure no fertile GM guys make it out of the hatchery, and what safety methods are there to keep these guys out of open water even if they are fertile.

I think there's ways to use this technology safely. I also think that there's too much suppression from the "no frankenfish" types that are more concerned with unscientific fears than the scientific fears. That's my concern - that we take the real threats seriously, but don't bow down to organic anti-industrial types that abuse legitimate concerns to force their agenda out. Not accusing anybody here personally, but the idealogues are plenty and are the loudest misinformers out there when any genetic modification is on the table.

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What I'd really like to know is the real success rate of induced polyploidy. What safety measures are in place to make sure no fertile GM guys make it out of the hatchery, and what safety methods are there to keep these guys out of open water even if they are fertile.

I think there's ways to use this technology safely. I also think that there's too much suppression from the "no frankenfish" types that are more concerned with unscientific fears than the scientific fears. That's my concern - that we take the real threats seriously, but don't bow down to organic anti-industrial types that abuse legitimate concerns to force their agenda out. Not accusing anybody here personally, but the idealogues are plenty and are the loudest misinformers out there when any genetic modification is on the table.

We've had this discussion before. The polyploidy success rate is about 97%. So for every 10,000 fish produced (a small level of production), 300 will be fertile. That amounts to thousands of fertile fish produced annually for even a modest production rate for a given aquacultural center...

...and it is statistically inevitable that those genes will escape once those fish can be bought.

Do you really think you can make a rule that will be universally followed? The consequences of ignoring rules (which ALWAYS ALWAYS ALWAYS happens) is that those genes will enter the wild and then whatever the effects become real instead of inferred. Once these genes are in the population, they can never, ever come out again. To say otherwise and to use these phrases like "scare tactics" and "unscientific" reflects a saddening unfamiliarity with how aquaculture, fish biology, gene flow and ecology actually work.

I've had aquaculturists assure me 100% that their stock have never escaped only to sample and find a third of the assemblages around their farms consist of their escapees and descendants. In that case, they didn't know what was happening. In many cases, they simply don't care. Being environmentally responsibile doesn't make them any money. Crash wild salmon? It will only help their profits.

Do you really think once these fish are available commercially that companies who's only moral imperative is to make money will follow the rules? They haven't so far. Where will this great enlightenment suddenly come from?

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Tim,

Thanks for the reminder on the %. I remembered talking about it before but couldn't recall the exact #.

I'm not saying that any rule would be 100% followed, but multiple steps of QC can reduce risks. For exampel 97% are sterile. Of the 3% that are not, QC blood sampling by the USDA could reduce the number of those that are put into farm population by another %. Now there are a few fish in the population, and I have to believe that some of those will escape, but what are the real numbers then? Then if a fertile fish, missed by QC, escapee makes it into the wild, it has to not be caught or killed, then it has to successfully make a strenuous trip up stream to a spot that it would like to spawn (shouldn't have the drive for this since it was born in a hatchery) and then be successful at spawning, which is not a 100% guaruntee for fish that ARE born with the drive to swim back upstream to spawn, and are better than the GM hatchery guys at spawing. Now if all that happens, those young have to have the gene which is probably 50/50 genetically, and they also have to successfully repeat the procedure for a few generations using their superior genetics as an advantage.

I get that we can't unring the bell if the gene gets out. I do think that reasonable multi-step rules could make the risk negligible. It's diminishing returns. This is not the "it only takes one" scenario.

Also are these fish polyploids from the normal process, or from a GM process? If so I think your 97% would be significanly higher.

I'd also prefer these things to be started in inland fish farms for further risk reduction. I thought that was the plan anyway.

And I don't think we can pretend like there's not a big anti-GM food movement that has nonscience as it's ideal. They're out there, I'm not saying it's you, but it's a big deal. "you don't know what it will do to you," "They use VIRUSES to make the corn that way." etc.

Just some thoughts.

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Are these fish available commercially right now?

Under testing for FDA approval right now. That's probably what funded this study.

The "never stop growing" gene is owned by a company called "Aqua Bounty" or something close to that.

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