The fact that it can’t survive by itself and that its depended of other fishes takes away the sustainability for me. The fact that they are getting viruses because of the close space means that Its not a stable way for the salmon to live. We are compromising the salmon existence just to satisfy our desire of money and fish. 

There is no sustainability is farms, is just an easier and safer way to hunt fish because one already have it. Its seams that with the way we are going we will cause the extinction of this animal, not his long lasting survival.