Wild salmon are born in fresh water and move out to the ocean.
When they return to the stream where they were born, they will stop eating and just live off the stored energy in their bodies. Consequently, it is best to catch them before they re-enter fresh water; after that, their flesh will lose colour and flavour.
In the wild, a 4 year old salmon will weigh about 40 pounds (18 kg), depending on where it was caught (Great Lake salmon will only reach about 15 pounds / 7 kg .)
Pacific and Atlantic salmon aren’t actually closely related.
Language Notes
In German, when salmon is genuinely caught in the wild, it can be sold as “Wildlachs”: wild salmon. Producers of salmon that is fish farmed in cages in bays, fjords, or the sea, will use the marketing phrase (“Verkaufstrick”) of “Wildwasserlachs” ( “wild water lachs”), but it is still classed as farmed fish. Salmon labelled “Wildlachs” is more expensive.