Salmon
Salmon are one of the largest fish you can catch, weighing in at 4-6 lbs. 1 pound of salmon will fill almost all of your hunger bar. They are, along with trout, one of the best available foods.
They are quite rare, and can only be caught in rivers and seas. Fish in rapids for a higher chance. Nets will also catch them.
A pile of 19 6-pound salmons cost one cord to dry or smoke, same as 19 perches or 19 meat cuts. Therefore it's most economical to dry/smoke salmon/trout instead of meat, though it may take a lot of time and equipment to procure more than just a few.
URW Game Encyclopedia description
The official URW in-game encyclopedia (accessed by the F1 key) doesn't have a separate entry for salmon, but in the entry on Fishing, it mentions salmon and salmon-fishing in the following paragraph:
The fish to be caught depends on the fishing method, equipment and the fishing site. Different kind of fish live in shallow or deep waters, lakes or rivers. Perches, roaches, breams and pikes are the most common fish living in lakes. Salmons are found only in rivers, and especially in rapids during their spawning season. There are also lavarets, trouts, pike-perches and so on.
