i agree, it would be pretty tough to fool a chef who knows anything about fish....HOWEVER...
the farmed king salmon are really nice fish; they have the flavor of the king salmon (usually wild caught) but are marginally fatter. farmers increase the fat content of the fish because the richer, fattier texture sells better. if you bought fillets, you would be hard pressed to tell the difference between the farmed and the wild fish. i am not confident that I could tell the difference, and i sold over 300 lbs of salmon, 55 hours a week retail for 7 years.
the caveat here is on atlantic salmon only. there are NO wild caught atlantic salmon in distribution, they are federally protected on the endangered species act. they are NOT endangered becuase of fishing pressure, they are endangered because of habitat destruction. when we remove the dams from the eastern seaboard, they may return. anyone selling wild caught atlantic salmon is either lying or has been lied to.
in fact, i would like to take this time to sing the merits of farmed salmon...
farmed salmon is fatty, mild, and cheap. for the last 40 years these have been the driving factors in the salmon trade. the first salmon farms, in norway circa 1960, were dirty, polluted heavily, and were inefficient. the vanishing numbers of atlantic salmon were the farms saving grace, and the "norweigan salmon" became a household name. any "norwiegan salmon" is farm raised atlantic salmon.
the wild caught pacific salmons were mostly canned or smoked until a couple of decades ago; the firm texture and strong flavor was undesirable until alaska started marketing it as a fresh product. the "copper river" salmon, was used mostly in fish meal and canned products until this time. the fish out of the pacific are indeed very tasty fish, the king salmon is my favorite fish of all time.
to be honest, i dont think the wild/farmed debate makes as much difference as the species of salmon. the king is ALWAYS going to be more flavorful and firmer than the atlantic salmon, be it wild or farmed. since the farmed kings are fatter, they more closely resemble those famed "yukon river" kings that fetched upwards of 30$ a lb last year than the wild fish do.
the contaminant levels of wild/farmed are roughly the same; that famous article in the NYT last year was all smoke and mirrors, every reproduction of that study has found that wild fish are either slightly MORE contaminated than farmed fish, or that the levels of contamination are pretty close. the group that funded that first study is the EWG/pew, notorious for cooking the results.
salmon farming is very eco-friendly. the concerns about fish escaping have been proven unfounded in the last two years, with escaped fish lacking the survivability of wild fish. yes, fish escape. no, they do not live long enough to compete with wild fish.
salmon farming is nearly pollutionless. after decades of refining the techniques, computer and camera controlled feeding has made fish farming, and salmon farming, some of the most efficient farming in the world. a normal salmon FCR is 1.1 or 2.1, with one lb of food for 1 lb of yield. no other protien can claim such a good food conversion ratio. the amount of waste that a salmon farm produces is marginal: i have heard it analogized as a couple of drops of pollution in an olympic sized pool. yes, its pollution...but its not much, considering the amount of product produced..
why have you heard opposite all these years? becuase the fish farmers dont have any lobby, and because the information being expounded is out of date. the beef lobby blocks all that bad press by buying there own studies, they are huge and untouchable...but the fish people are an easy target because they are not conglomerated or organized, and they lack the resources to fight back. fish farming has come leaps and bounds over the last ten years, and is much cleaner and more efficient than it was 5 years ago. the press cant update fast enough, and no one wants to read good news. for one, i am tired of fish farming getting all this bad press. farmed atlantic salmon are GOOD, they are just a different product than the pacific salmon. different species altogether, kind of like comparing a duck and a pigeon...hey, they are both birds, right?