Response to comment: salmon

In terms of sustainability, any wild salmon will do. Don't be fooled by "organic" Atlantic salmon; it is still unsustainable, although perhaps slightly less filthy. Atlantic, i.e. Norwegian and Scottish salmon are farmed. Alaskan (Coho, King, Sockeye, etc.) is wild. In terms of taste, Coho and King have a richer flavor, but for salmon burgers and everyday use, Sockeye is great and slightly less expensive. Even Target has stopped selling farmed salmon.

Mark Bittman votes for King and links to an article which in turn links to an expose film with disturbing images: This is one of four. See the others below.