Lay the fish on the work-surface, hold it by the tail with the left hand, and gripping a knife in the right, scrape down the fish starting from the tail, then wash under cold running water.
Cut along the full length of the belly of the fish starting from the lower part.
If the fish is going to be grilled, gut it without removing the scales.
Remove the innards and cut them up.
Insert an index finger inside a gill and pull strongly to extract it completely. Then wash the inside and outside of the fish under cold running water.
Using a knife, cut into the bone behind the head and remove the bones.
Working parallel to the work-surface, cut away the skin of the back from the head to the tail, moving the knife with a sawing action. Finish by detaching the upper fillet.
Perform the same operation for the lower part of the fish, in this way completely eliminating the bones.
Even up the fillets by removing the membrane and the parts with blood.
With the aid of a knife, remove any remaining bones from the back.
For a salmon of 3kg, there will be waste of around 1.4 kg equal to 45%.