In a large heavy-bottomed soup pot, melt butter over medium-high heat. When butter is hot and bubbly, add onion, garlic and bell pepper and saute until softened, about 5 minutes. Stir in potatoes, stock and black pepper. Bring to a boil, reduce heat to low and simmer until potatoes are tender, about 10 mintues. Add salmon peices and cream, and simmer over low heat until salmon flakes easily with a fork, about 5 minutes. (Do not boil).