Salmon in the Classroom
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Salmon Lifecycle

Lifecycle of Salmon
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Salmon Eggs
Salmon eggs

Eggs: Adult salmon lay their eggs in special nests in the gravel called redds in late autumn in freshwater.

The eggs hatch in the spring time (depending on water temperature) into alevins.



Alevins: Hatch in spring time whilst still under the gravel. They have yolk sacs which they use for food whilst buried in the redds.

They emerge from the gravel about four to six weeks after hatching (depending on water temperature).


Salmon Fry
Salmon fry

Fry: After the yolk sacs have been used up, the alevins have to start to feed. At this point they are known as fry. They feed on tiny water organisms and grow quickly during their first year.


Salmon Parr
Salmon parr

Parr: The salmon are known as parr once they are over a year old. They stay in freshwater for between one and four years, feeding on small insects and growing larger.


Salmon Smolt
Salmon smolt

Smolts: The parr change into smolts in the spring of their second, third or fourth year. This change from parr into smolts is the process where the salmon are getting ready to head out to sea. Smolts head out to sea in shoals during late spring. They are a very distinctive silver colour.


Adult Male
Adult male

Adult salmon: Adult salmon travel great distances at sea to rich feeding grounds in cold northerly waters and feed on sandeels, krill and herring. The salmon return to the rivers in which they were born after being at sea for one to four years.


Adult hen

Adult salmon that return to spawn after one year at sea are known as grilse. Adult salmon that stay more than one year at sea are known as multi-sea winter salmon. Once the salmon start their journey from their feeding grounds, they do not feed even when they are back in our rivers.



Kelts: After the adult salmon have spawned they are known as kelts. The females have laid all their eggs and appear particularly thin. The male fish are tired out from fighting with other males to make sure they spawn with the best females. Some kelts are able to make it back out to sea, where they will begin to feed and grow strong again. If they are very lucky they may be able to survive long enough to make it back to their river again to spawn.

Scientists estimate that only around 5% of kelts that make it back to sea, and survive, are able to make it back to spawn in our rivers!

Salmon Habitats