Cook pasta in boiling, salted water until al dente. Drain. Drain the can of salmon over a 2 cup measure. Add enough milk to make 1 3/4 cups.
Meanwhile, prepare sauce. In a large saute pan, melt butter over medium heat. Add onion and mushrooms; saute until onion is tender. Reduce heat to low, and stir in flour. Remove from heat.
Stir into cooked vegetables, the milk mixture and wine. Return pan to heat, and bring to a boil, stirring frequently. Reduce heat, and simmer for 2 minutes. Break salmon into chunks; stir into the sauce. Stir in Parmesan cheese, parsley, and dill. Season with salt and pepper to taste, and heat though. Serve over hot pasta.