I found this on another cooking website when I was looking for a recipe to create Lobster Base. "Betsy" was the contributor. It was on recipelink.
Combine all ingredients in a large sauce pan. Bring to a boil. Reduce liquid to about one cup. Separate solids from liquid. Base can be frozen for up to 6 months. Cooking time will vary as will servings depending on recipe and how the base is used.