Wild Salmon Unlimited — From the wild to the wild

Resources

Life Cycle of Atlantic Salmon

Seven stages, from a buried egg to a returning adult.

  1. Salmon eggs in river gravel

    Eggs

    The eggs (ova) begin developing right after fertilization and, depending on water temperature, will hatch in the spring.

  2. A newly hatched alevin with its yolk sac still attached

    Alevins

    The just-hatched fish are called alevins and still have the yolk sac containing food attached to their bodies. When most of the yolk sac has been consumed the alevins become active and begin their journey up through the gravel of the riverbed.

  3. A salmon fry in shallow water

    Fry

    The fry have eight fins, used to maintain their position in fast flowing streams and manoeuvre about in the water. Their survival is temperature dependent and heavily influenced by predation, pollution and competition for food.

  4. A salmon parr showing its vertical camouflage stripes

    Parr

    Over the autumn, the fry develop into parr with vertical stripes and spots for camouflage. They feed on aquatic insects and continue to grow for one to three years while maintaining their territory in the stream.

  5. A silver-sided salmon smolt

    Smolt

    At a length of 12 to 24 cm (4.7 to 9.5 in.) during springtime, parr transform and become smolt. A silvery sheen replaces the parr marks, and internally they undergo a complex transformation to survive in saltwater.

    More about smolts

  6. An adult Atlantic salmon

    Adult Salmon

    Grilse are salmon that reach maturity after one year at sea; these return to their river in summer weighing from 1 to 4 kg. If it takes two or more years at sea to mature, the salmon will return considerably earlier in the year and larger, at 3 to 15 kg. These big fish are highly favoured by anglers.

    Salmon exhibit a remarkable homing instinct, with a very high proportion able to locate their river of origin using the earth’s magnetic field, the chemical smell of their river, and pheromones released by other salmon in the river.

  7. A redd — the gravel nest a female salmon digs to spawn

    Spawning in a Redd

    Wild Atlantic salmon spawn in late autumn. The female digs a nest 10–30 cm (4–12 in.) deep, called a redd, in the gravel bottom of the river, where the eggs are laid and fertilized before being covered over again.

From the Wild to the Wild

WSU’s smart stocking works with this cycle rather than around it.

How smart stocking works