Lesson plan: basic habitat requirements
Atlantic salmon require two distinct habitats. As adults they need deep, cold water with lots of prey fish. As juveniles they need coldwater streams. For most populations of Atlantic Salmon the adult habitat is the northern part of the North Atlantic Ocean. For a few populations large, deep lakes serve as an alternative to the ocean; Lake Ontario is one of these lakes.
When adults are ready to spawn they migrate from the ocean or lake upstream to find a shallow area with the right amount of current and a bottom consisting of gravel. Eggs are laid and fertilized in the gravel in nests called “redds”. The eggs, protected in the gravel, develop into juvenile fish. The young fish hide in the gravel and hunt aquatic micro-organisms like zooplankton and macro-invertebrates like mayfly larvae and blackfly larvae. It is essential that this habitat has clean, cool water. A major component to healthy stream habitats is the health of the land. A supportive landscape with lots of tree cover helps to keep the water cool, reduces sediment caused by erosion, and helps to keep pollution out of the water. Leaves and branches that fall into the water provide food for the small creatures that the juvenile Atlantic Salmon prey on. After 1-3 years in the stream habitat the juvenile fish are big enough to migrate to the big water habitat.