Great Boston Globe article on the dangers of farm-raised salmon and how it hurts more than helps. This is similar to the argument against GM crops; they simply don't help and actually hurt the environment.
Sadly, I'm surprised that the US actually passed a law last year banning certain kinds of seafood from China due to the antibiotics used. Sadder still, I wasn't surprised in the least that the FDA doesn't test yet for "SLICE", a heavy-duty pesticide used to fight off sea lice in farm-raised and wild salmon populations.
Instead of just leaving the salmon in their natural habitat, we've created a monstrosity with all of the world's salmon populations via this great idea of "farm-raised" salmon. Farm-raised, contrary to what some believe, does not mean salmon are shut off from natural populations, being raised in tanks. They are merely captured in nets (and kept in the ocean in those nets) to breed, with some escaping after disease spreads quickly among the tightly-packed salmon inside the net, after which disease begins to also spread to the natural populations swimming by.
This is all aside from the fact that salmon taste better when wild due to the strength that is built up via natural selection among the members of the species that survive to adulthood: you've all heard how salmon swim against the current, then with the current, then against the current to breed; this only happens amongst those salmon which are naturally equipped and strong enough to do so. Allowing all salmon to breed, regardless of strength or quality, in an unnatural environment, is a bad idea. Hmm, might this also apply to humans?
Haven't we learned enough from this horrible experiment? Are we really willing to kill off the entire species just to prove a point? The world cannot sustain nearly 7 billion people all craving the same type of food. Overfishing because a certain type of fish (read: lobster) is fashionable proves the point that we need to reduce our numbers drastically and live in a more natural way. Trying to mine the hell out of the salmon population to make a few extra bucks isn't worth it, and all it's doing is accelerating the death of the species.