Fish farming isn't going to expand everywhere just because you say it is and no-one is saying they should be able to in spite of your suggestion to the contrary. You're attempting to set up a fallacious argument; developing erroneous premises that suit your personal, unscientific conclusions. In other words, it's nothing more than meaningless rhetoric in support of your attempts to paint salmon farming as evil.
If farms are going to expand, they will only do so in areas that meet very specific biological, oceanographic, environmental and legal criteria. They will only do so if there is a sufficiently undersupplied market to absorb the production and they will only do so after following a fairly rigorous approval process.
It is not a fallacious argument to say that if there is an established industry already in BC and another player wanted into the market, then the industry would expand. Competition laws demand it. The fish farm industry has already expanded, even under a moratorium on new farms, by expanding capacity of existing operations. You have stated repeatedly that fish farms are necessary to meet a high world demand for salmon that cannot be met by wild salmon, therefore, it stands to reason
that this "demand" will continue to rise with population a drive expansion. It stand to reason
that if allowed to expand, the fish farm industry would. The very fact that there needs to be "very specific biological, oceanographic, environmental and legal criteria" supports my argument that they have a negative effect of the natural ecosystems.