Pat the salmon filet with a paper towel to remove any excess moisture from the salmon. Set aside.
Add the coarse sea salt, garlic powder, smoked paprika, chili powder, mustard powder, and brown sugar to a small bowl and mix to combine.
Sprinkle the dry rub on top of the salmon and gently massage it into the flesh.
Refrigerate for at least 1 hour (and up to overnight).
Prepare your smoker with wood pellets. We used Traeger's signature blend. Preheat your smoker to 225ºF and remove the salmon from the refrigerator. Let the salmon sit at room temperature for 10 minutes. When the smoker is ready, place the salmon filet skin-side down into the smoker and cover. Smoke at 225ºF for 1 hour.
Next, make the maple glaze. Add the maple syrup, soy sauce, and worcestershire sauce to a bowl and whisk to combine.
After 1 hour of smoking, brush the salmon filet with the maple glaze and increase the smoker temperature to 375ºF. Cook the salmon for an additional 10 minutes.
Remove the salmon from the smoker when the internal temperature reaches 145-150ºF.
Let the salmon rest for 5-10 minutes.
Top smoked salmon with capers and eat immediately or place the salmon in the refrigerator to cool and serve cold.