Bring a large pot of salted water to a boil and cook the whole wheat spaghetti according to package directions until al dente.
While the pasta cooks, season the salmon fillet with half of the sea salt and black pepper.
Heat the olive oil in a non-stick skillet over medium-high heat and sear the salmon for approximately 4-5 minutes per side until it is opaque and flakes easily.
Remove the salmon from the pan and set it aside to rest for a few minutes, then flake it into bite-sized pieces using a fork.
In the same skillet, add the trimmed asparagus spears and minced garlic, sautéing for 3-4 minutes until the asparagus is bright green and tender-crisp.
Drain the cooked spaghetti, reserving two tablespoons of the pasta water, and add the noodles to the skillet with the asparagus.
Incorporate the flaked salmon, lemon juice, lemon zest, fresh dill, and the remaining salt and pepper into the skillet.
Toss everything together gently over low heat, adding the reserved pasta water if needed to create a light sauce, and serve immediately.