After having fished in S.E. Alaska for Trident Seafood in the purse seine fishery, I can not see this being a problem with wild caught salmon...
Our fish were put live, in a refrigerated sea water hold, (below 40 deg F).... Delivery of those fish was daily to a tender or the cannery, often still alive.... I can't say what the tenders did with them, but there were some pretty stringent rules for the seiners to follow, and lab techs, in white coats, would board us periodically also...
Considering the "long line" method and species of fish named, it is the warm water species that looks to be the culprit.... maybe even farmed fish from the tropics....
JJ Thanks for the article..... Now I have another reason to not eat farmed fish, especially from Viet N-m and Ch-na....