Land Tuna and PNP:
I agree with most of what you said, especially PNP point that dollars drive decisions, not what is best for the environment and consumers.

However, the issues I understand you to hinge your position on are, in short:
1. Pollution to the sea
2. Bio-Mass required to produce fish is too great

Do you feel that the above 2 issues just cannot be overcome? I expect they could be, and it wouldn't take much. If Shamoo can live in a tank ON LAND, (I certainly don't condone this) and human wastewater can be treated and discharged, why not apply the same requirements to fish farmers?

If the fish are on land in tanks, it takes away escapment, and if the waste is treated in our existing sewer system, much like paper millls, etc., and uneaten feed is recaptured and recycled, doesn't that do it?

Other points you raised are certainly important, such as, wild salmon provide us a reason to keep their environment clean, and calorie to calorie, this will not be an efficient way to feed the world's population. But I view those 2 issues as separate, moral issues.

There should be plenty incentive to maintain healthy waterways, and while Land Tuna is probably correct, I still think that providing an option to any fish consumer to eat a safe, environmentally responsible, raised pen fish is better than that same person purchasing a Puget Sound wild salmon.

Are Goeduck and I woefully ill-informed, or just not living in reality?

The only piece my reasoning doesn't address is: It just seems weird to see such a great creature living in a tank in a field. Hmmm. That might be reason enough to abandon the idea.