Atlantic salmon have a complex life history which starts when adults come into rivers from the open ocean to spawn every summer and fall, with spawning migrations lasting from June through to November. Salmon also return to the same river systems they were born in year to year, and from generation to generation, in order to spawn. A female will choose a site where the gravel is “just right” in order to “dig” out a nest with her tail. The salmon will then form pairs and spawn over a period of two to three days, with the male guarding both the female and the gravel “nest” during spawning. A female will release 8,000 to 25,000 eggs, which the male will cover with gravel after fertilizing. Eggs hatch after 70 to 160 days, typically in the spring, where they will remain deep in the gravel until their yolk sac has been completely eaten up. As they continue to grow, they will emerge from the gravel and move to shallow pools downstream of where they hatched. They may remain in freshwater environments for one to seven years, however most only stay for two or three years. The salmon will then undergo physiological changes, through a process called smoltification, after which the newly developed juvenile salmon, or “smolts”, will move out into the sea.
Once in the open ocean, Atlantic salmon feed on squids, shrimps and smaller fish. They reach sexual maturity between three and seven years of age and will begin their annual migration inland to spawn and complete the lifecycle. Atlantic salmon, unlike many of their Pacific salmon counterparts, do not always die after spawning and may return to spawn again the following season. These “repeat spawners” are especially important in populations of Atlantic salmon because they are larger and are able to produce more offspring than first time spawners.
