Abundance of spawning populations may differ greatly between years. For example, in the Fraser River in British Columbia, the odd-year run includes nearly 20 million adults whereas the even-year run is virtually nonexistent (Beacham et al. 1994). However, this pattern is not evident in all river systems.
Young form schools in estuaries before moving out to sea. Predators of young salmon include: cutthroat and rainbow trout, Dolly Varden, kingfishers, mergansers, etc.