Someone on my Facebook is claiming that the genetically-altered salmon that should be approved by the FDA later this month are going to be a big problem for native salmon populations. I understand most of his concerns, but he claims that, “…one fish escaping and interbreeding with any salmon population would mean an irreversible germ line change for an entire species”.
I tried to google it, but only found links to technical documents that I found difficult to parse.
Are these genetically manipulated fish going to spell doom for native populations? And if so, how?
“Germline” means that the alterations are inheritible - unlike (say) a mutation in a person’s skin cell that causes skin cancer, but does not affect any children of that person, a germline change will be inherited.
No idea if the gene is dominant or if the altered salmon can interbreed with native salmon - sorry.
If the inheritable alterations aren’t to the benefit of the species (in terms of survival) then they won’t stay around for very long. The only way I can see the alterations sticking around is if they are either beneficial or neutral, in which case I don’t see what the big deal is.
That’s sort of what I was thinking. He was making less than subtle intimations that he found genetically modified fish ‘unnatural’.
.02/** Frankly, if we Pacific Northwesterners really cared about the longevity of wild salmon we would do more than complain in-passing about dams and accept that severely limiting the fishing season (both commercial and recreational) will piss people off in the short term, but be effective in letting the species bounce back in the long. **/.02
Sure, that’s their opinion, but we are dealing with a factual question here i.e. “Are these genetically manipulated fish going to spell doom for native populations? And if so, how?”
As far as I can see the answer is ‘no’, natural selection won’t let weak genes take the place of healthy ones to the extent that the species would be doomed. The species may take a hit for a short period but eventually the genes passed along by the modified salmon will be bred out (if they aren’t beneficial that is).
The major issue I see with any GM food - plant or animal - has more to do with monoculture. A perfectly acceptable change (bigger, stronger) may be an advantage to a species and work its way into a large amount of the population.
Where did that gene come from? Odds are a small sample of fish (or whatever) were given the gene and then heavily inbred to become a commercial farm population. SO the variability of the gene pool is small. This is not a big deal in a farm population protected, nutured and sheltered by man. Once it escapes into the wild - it may have bad side-effects.
Imagine a gene for “twice as big”. That may cause the larger salmon to win the mating rituals, etc. and dominate the gene pool. Then comes the “lean years” and the salmon experience a massive die-off because the reason wild salmon did not usually get that big, was because in lean years the big ones die sooner from hunger.
Maybe the process is self-correcting in time. Maybe mother nature does not care if salmon survive as a species or not… Why find out the hard way?
It’s possible that the modified genes would be advantageous to the salmon species, but disadvantageous to the ecosystem as a whole. For example you might end up with bigger/stronger/faster salmon that can now outcompete other medium-large ocean predators. This could damage the ocean ecosystem as a whole, and threaten commercially valuable species like tuna (which in many cases are already threatened by overfishing). Alternatively, you could have genes that are advantageous to the salmon in the short term and get fixed into populations, but are disadvantageous in the long term. Like md2000’s example where a bigger/stronger/faster variant is advantageous when resources are plentiful, but strongly disadvantageous when resources are scarce. That could cause a temporary boom in salmon populations followed by dramatic collapses.
However those are really worst case scenarios. Most of the time I’d suspect that any genetic modifications wouldn’t be advantageous in the wild. Aquaculture isn’t interested in bigger/stronger/faster super salmon, but rather bigger/fatter/more docile strains.
How many domestic animals can outcompete their wild counterparts?
And, really, we’ve been genetically modifying species for tens of thousands of years, for better or worse. Modern techniques just speed up the process and introduce some new possibilities.
He’s right, they are unnatural. Whether that’s good or bad is a matter of opinion, but if “unnatural” is the term of choice for species that humankind has fiddled with, then GM salmon are indeed unnatural.
So are farm animals and crops. Even the ones whose genes haven’t directly been tweaked in a petri dish: selective breeding of plants and animals is unnatural, too.
I don’t know if this is the state of things, but I can see how “genetic pollution” from escaped salmon could be an actual problem.
Farmed salmon are not selected for survivability in the wild, either as fry or adults, but for growing quickly in a controlled environment with a constant supply of food and with medication for any illnesses, this means they could have plenty of genes that would not be beneficial.
The fear of genetic pollution is not a fear of the odd farmed salmon escaping. It’s a fear of a constant influx of bad genes from a steady supply of escaping salmon.
With salmon stocks many places being vulnerable due to overfishing and other human factors, the farmed salmon might be a substantial part of the breeding population each year, even if they were so degenerate they didn’t survive for another season, which I believe they do.
Sure the bad genes will get bred out eventually, but in the mean time it will be another detrimental factor to already taxed populations.
If they are so poorly suited for survival in the wild, why would we expect their genes to spread far and wide and wreak havoc on the entire wild salmon population?
Maybe one gets out. Maybe it miraculously survives to spawn. But none of its offspring (or at least very few, compared with the usual results of spawning) would survive to adulthood. In very short order the genes would be extinguished.
That “twice as big” example sounds pretty close. From the Washington Post:
On the other hand, no, Mother Nature “does not care if salmon survive as a species or not.” Only the salmon care. And all the bears et al that eat them care. And, because we like to eat salmon and coo at bears, we care. But Mother Nature does not care. If the salmon go extinct, something else will eventually evolve to fill its niche.
With current salmon farming practices it’s not a case of “maybe one gets out”. If the wild salmon population in an area is small, as some of them are, and the density of salmon farms is high, which it is in some areas, then there’s a possibility of escaping salmon being a substantial part of any years breeding population.
This can be a problem for vulnerable stocks today, with just regular farmed salmon.
With genetically modified salmon you have the additional risk of permanently introducing whatever modifications have been done into the wild salmon population. Will that spell doom for the wild salmon? Probably not, but quite a few people think there are limits to how much we should meddle with nature.
This is the other interesting part - just how many different salmon genes do you think they modified? Odds are most farm salmon will have at least one gene in common. It may give them a trait which allows them to out-compete the natural salmon in most circumstances; but if that gene has one fatal flaw - susceptibility to disease, or unable to survive hard times like drought or food shortage - then suddenly their population will fail dramatically with repercussions.
(Think Irish Potato Famine… one little blight, one massive global demographic shift.)
You stick monkey wrenches into the giant wheels of nature at the risk of destroying large chunks of the ecology if you do not truly understand the complete workings.
Even simple things have odd consequences - in western Canada, cattle have passed tuberculosis to wild animals; we can isolate and treat cattle, but the disease runs rampant now in the wild.