The simple answer to all this nonesense is "market driven" . Near Yellowpoint,south of Nanaimo there are several sites that have land based fish farms and they are doing very well. The local Grocery firm(Thrifty Foods)markets these as" Eco " raised Salmon...they do charge more for these fish but is it not worth it. Many people do not realize that some Salmon ,since Time began,(fish time that is),have lived much of their lives in Fresh Water lakes. For example,Atlantic Salmon are Native to Lake Ontario ,until the St. LAwrence Seaway was constructed there were good numbers of fish entering the lake. Also,and a good example of why pacific Salmon do not thrive well in fresh water are of course our "Kokanee" ,Stranded Sockeye!
Water movement,like air movement for we humans,is critical if farmed fish are to survive in such confined quarters. And there has been work done in lakes for fish farms.
I was just talking to an ex:commercial fisherman who now guides we sporties out of Ucluelet and he was telling me of the sheer numbers of fish being taken..His example to me was his good days for Sockeye out of "Hardy' would be 5-600 fish per day. When the Seiners came in they would take 60,000 lbs/day/boat...more than his total year.
There is no wonder we have very endangered runs of fish everywhere along our coast.
C