I think that the published letters from the opponents to salmon farming miss two points, though I share their concerns for the health of the wild fish.
The first point is that if we are to be able to feed the burgeoning human population it is essential that we must farm fish as we do cattle, hogs, sheep and chickens.
This morning I saw an item in the news that the human population will reach seven billion by the end of this month, and a large part of that population is close to starvation.
The second point I see is that the problem is not salmon farming per se, but the open pen system in use, which means that the wild salmon are effectively exposed to all the effluent and pathogens from the farmed fish.
With the exception of the huge cattle ranches, our domestic livestock are generally segregated from their wild counterparts.
Perhaps the advent of Mad Cow disease in the buffalo herds of the Wood Buffalo National Park might have been due to contact with infected ranch cattle.
If that were the case, it would point out the danger of raising farmed livestock, including fish, in the same area as their wild counterparts.
I look forward to reading of the success of the closed-pen fish farms, and hope that it leads to all farmed fish being raised in isolation from the wild fish.