Cook pasta according to package directions or bring 4 quarts of water to a boil, add half a teaspoon of kosher salt to the boiling water then drop the pasta in, stir, and cook 10-12 minutes until al dente. Drain.
Prepare the creamy dressing by adding the mayonnaise to a small mixing bowl. Next add the lemon juice, salt, pepper, onion powder, Tony Chachere's Creole seasoning, capers, and chopped dill to the mayo then stir to combine; set aside until needed.
In a large bowl add the cooked shell pasta, bell pepper, green onion, celery, and drained salmon. Transfer the creamy dressing to the mixing bowl with the other ingredients and use a spatula to mix until everything is combined.
Cover with plastic wrap and chill until ready to serve.
When serving, garnish with chopped parsley, if desired.