Eggs, Incubation and Hatching Protected by their gravel cover and shaded by overhanging vegetation, the salmon embryos incubate in the redd for up to 4 months. If stream side erosion and siltation are not a threat, water temperatures will remain cool enough, and circulation adequate, for up to 40% of the eggs hatch. Tiny 15-20 millimetres alevins are released, fish-like forms with spotted backs, black eyes and small yolk sacs attached to their bellies. The alevin remain in the gravel until they have used up all of the yolk sac, or become buttoned-up.

Fry, Fry Emergence By spring, the 2.5 centimetres salmon are known as fry. Still sensitive to light, they move out of the gravel into sheltered deepwater and begin to feed on plankton, insect larvae and water nymphs. In some species, salmon fry begin to move almost immediately downstream toward saltwater. Many salmon are lost at this stage to predators and poor water conditions.

Parr and Fingerlings When salmon reach about 5 centimetres in length, they are called parr or fingerlings. Most will have some kind of parr marks, or dark spots and stripes on their sides to camouflage them in their streams. Parr marks on species which go directly to the ocean, such as pinks and chum, are faint.