A good salmon life cycle book is Margaret Craven's "I Heard the Owl Call My Name." It's for adults, but I read it as a young child, and I think it would likely be fine for a mature eight year-old. A couple of caveats: the main character, a priest named Mark, dies of cancer at the end of the book; his death is beautifully compared to the return of the salmon. Other adult themes to be aware of (as far as I can recall, anyway) are the decision of one character to bear a child out of wedlock, and the government taking First Nations children away from the village to a residential school.
There are other salmon stories in Christie Harris's Mouse Woman books; these books are meant for children.
Hope that helps a bit--
peace
minnie
