Much as I enjoy cheap fresh salmon, I agree that farming offshore, which is done in Canada as well, has been a bad idea, no matter how commonsense it looked in the first place. Not just diseases, but also escaped farmed fish breeding with wild salmon has consequences.

I'm boggling at the visual of massed jellyfish actually slowing down boats. I try to like jellyfish, I really do, and they are quite pretty, as long as they're not closer than five metres. But I had this experience as a child, running on the shore. I was well onto a stretch of sand, every inch of it covered with transparent flat moon jellies, before I realised what I was running on. I just kept running, expecting to reach the end of them, but no such luck - they went on and on until I ran up into the rose bushes and brambles to get off them... the sensation is indescribable.