In October, drawn by natural forces, the salmon return to the rivers which gave them birth. They fight their way upstream against powerful currents, leap waterfalls and battle their way through rapids. They also face dangers from those who like the taste of salmon: bears, eagles, osprey and people.
Once the salmon reach their spawning grounds, they deposit thousands of fertilized eggs in the gravel. Each female digs a nest with a male in attendance beside her.
By using her tail, the female creates a depression in which she releases her eggs. At the same time, the male releases a cloud of milt. When the female starts to prepare her second nest, she covers the first nest with gravel which protects the eggs from predators. This process is repeated several times until the female has spawned all her eggs.
Their long journey over, the adult salmon die. Their carcasses provide nourishment and winter food for bears, otters, raccoons, mink and provide nutrients to the river for the new generation of salmon, much as dying leaves fertilize the earth. Click on the image to see a larger version.