When I first started researching oils many years ago I found that most “fish” oils either came from the gulf (menhaden) or Chile (anchovy and herring). Salmon oils were predominantly from Norway or Nova Scotia (Atlantic salmon) and farm raised in standard net pens or “deep sea” net pens common in the North Atlantic. One of the major suppliers of fish oils in the US told me their “Salmon” oil was mostly anchovy oil and had little to no salmon oil at all and if it did it was from farmed fish. The problem with anchovy, menhaden, tuna etc. is that the oils must go through molecular distillation to make them safe thereby reducing the natural benefits the oils provide. Wild Alaskan salmon oil that is “polished” or “cold filtered” has lower heavy metal counts than most “fish” oils that have gone through molecular distillation except that all of the Omega fatty acids remain intact.