In my local area, Co-op, Home Depot carry Bear Mountain pellets, which has Alder as the base wood. Alder has lower BTU's and produces a fair amount of ash. If you're smoking Salmon, it would be a good match, as that is the traditional smoking wood of the west coast American natives. If you're using an A-MAZ-N tube smoker or equivalent, you may have issues with keeping it lit when using lower wood with lower BTU's, as it doesn't generate sufficient heat, especially if it's not getting sufficient oxygen.