Strange to have an article about salmon farming drawbacks without mentioning escaped salmons polluting the wild salmon population. There has been a strong decrease in wild salmon as they lose the ability to migrate back up the river to lay their eggs due to breeding with escaped farming salmon.
And, another could be to increase the populations of wild salmon
Dumber here is a feature, not a bug. The dumber the farmed escaped salmons are, the better.
Imagine 10 wild salmons swimming up the river to reproduce, 8 of then are devoured by bears. Only Rick and Jenny survive.
Now imagine the same salmons swimming up the river to reproduce, but joined by 40 farmed sterile salmons. And 8 of them are devoured by bears.
The reproductive success of the wild ones have increased, because security is in the numbers. Being easier to catch, bigger, clueless and extra-dumb, farmed salmons will attract the predators and more wild ones will reach the end.
The problem with this logic is that if 80% of the salmon in the water are sterile, then the probably of a fruitful mating is only 20% of the previous rate. For most wild populations, this is cataclysmically bad.
It works on screw worm flies. It will have a similar effect on wild salmon.
Philosophy is about logic, Science is about hypotheses. Salmon male sneak near couples mating, but first you need this extra male to survive to be able to do that
What I mean is that Biology is not simple. Things that you assume to be bad, may have also a positive side. You will never know until you do actual research and, unlike that five minutes read in a newspaper, finding the truth takes years of serious work.
Unless you spend many hours studying, you may never notice that 'kelp' forests are changing even in places without salmon farms. Without a single salmon farm, Spain lose 90% of their "kelp" (in fact Laminaria) forests in the 1990's. So maybe there are other hidden reasons for the change?
After years the ecologists understood that the problem with kelp was the sea temperature raising just one degree. This was enough to lose thousands of Km of submarine forests around all the North coast of Spain in just a decade. A good example of collapse of the entire ecosystem after minor changes.
Without spending hours studying, you may not realize that kelp war against green algae lasts for millions of years. Kelp evolved to be one of the fastest growing things alive and to build chemical defenses. If algae has the upper side suddenly, maybe there is more to see than the simple answer of "is contamination". What prevents kelp to use all this extra nutrients to grow instead?
Biodiversity is the biggest and more complex machine built in this planet, and tends to do unexpected things. Ideas like "monogamy: good", "cannibalism: bad" are useless in biology. Biology does not care about moral stances or tables of the law, and not always act as ideology would wish
I dont think thats the mechanism, otherwise there would be 0 effect on wild population. Farmed males spreading their genes must have some effect though, its not like they are automatically infertile due to just being farmed.
Similar approach works very well ie on tse-tse fly in parts of eastern Africa I've visited - introduce infertile/weak males into wilderness to effectively eliminate entire population in medium term.
I think the idea is that the migration instinct passed down by wild salmon is an epigenetic heritable trait. This trait is strongly selected for in wild salmon populations, but not in farmed populations. The constant influx of this maladaptive trait into the wild population is leading to an overall decrease in the ability of the wild population to successfully propagate.
That's surprisingly easy. It's been done for chickens. All that was necessary was to put groups of chickens in cages, and keep only the cage groups that were the best egg-layers. After only a few generations, chicken-on-chicken violence was way down.
