I normally make this with the tail sections of king salmon, but any salmon, trout or char will work here, as would whitefish. Whatever fish you use, it needs to be fatty.
Mix the salt and sugar together. Sprinkle a thin layer of this over the bottom of a lidded container. Arrange the strips of salmon in the container in one layer. Cover with the remaining cure. If you need to do this in more than one layer, heavily dust the first layer with the cure before adding more fish.
Cover the container and let this cure in the fridge for 12 hours. If you can, turn the container upside down once during this time, or mix the salmon pieces around, so you get a more even cure.
Remove your salmon from the cure and quickly dunk it in a large bowl of ice water to rinse off excess cure. Pat the fish dry with paper towels and set on a rack over a baking sheet in the fridge overnight if possible, or in front of a fan or in a cool, shaded, breezy place for at least 1 hour. You want the surface of the salmon to get sticky-tacky, which will help smoke adhere to it.
Fire up your smoker. I generally smoke at about 200°F. See the headnotes for your wood choices. Smoke you salmon for at least 3 hours, and as long as it takes to get dried, but still chewy. It normally takes me 5 hours. If you are using maple syrup, paint it on the fish every 30 minutes or so after 1 hour has elapsed.
Once you have salmon jerky, put it back on the cooling rack to return to room temperature. It will keep in cool room temperature, i.e., 60°F or below, for a long while, but I keep my jerky in small, vacuum sealed packets in the fridge until I need it. It should last like this for months.