Bob,
Your right about net pens not being the only option.
I do not have any hard studies in front of me, maybe Smala or Salmo would. From what I understand plants directly into salt water, and net pens, in the sound are being discouraged due to the amount of straying when the fish eventually find a river to spawn in.

I worked for Prince William Sound Aquaculture for a summer, and did not think about that as "fish farming", but I do see your point. Some things that scare me with hatcheries like those, that get millions of pinks and chums back, are what are the impacts of that many additional salmon at sea, could it starve out the wild fish. I do not know enough about the amounts of food out there, I'm sure it is great but thats an awful lot of fry to feed when they are released. Production levals of fry from some of the PWS hatcheries is 50 to 200 million fry each.

N.E.N