By Harold McGee
Salmon develop their muscle mass and fat stores in order to fuel their egg production and nonstop upstream migration, processes that consume nearly half of their weight and leave their flesh mushy and pale. Salmon quality is thus at its peak as the fish approach the mouth of their home river, which is where commercial fishermen take them. The stocks of Atlantic salmon have been depleted by centuries of overfishing and damage to their home rivers, so nowadays most market fish come from farms in Scandinavia and North and South America. The wild Alaska fishery is still healthy. Opinions vary on the relative qualities of wild and farmed salmon. Some professional cooks prefer the fattiness and more consistent quality of farm fish, while others prefer the stronger flavor and firmer texture of wild fish at their best.