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Salmon Life Cycle

Wild Atlantic salmon vary in appearance during their lifetime. Until the early 19th century the life cycle was not understood and documented, and Parr and Smolt were assumed to be different species of fish.

EGGS - Pea-sized orange eggs are deposited in riverbed gravel in autumn, and hatch the following early spring. As the eggs develop, the eyes of the developing wild salmon can be seen through the semi-transparent membrane.


ALEVIN - The partly transparent alevin hatch and remain hidden in the riverbed gravels, feeding from the attached yolk sac. They are about 2 cm or less than 1 inch in length.


FRY - Wriggling up from the gravels, fry begin feeding on microscopic life in the stream. They eventually reach a length of 5 to 8 cm./2 to 3in. before transforming into parr.


PARR - The vertical markings, called 'parr marks' appear, with a single red dot between. Parr remain in the river for 2 to 6 years, depending on water temperatures and food availability.


SMOLT - At a length of 12 to 24 cm/4.7 to 9.5 in. a springtime transformation of the parr takes place into smolt. A silvery sheen replaces the parr marks, and internally they undergo a complex transformation to survive in saltwater. On the downstream journey the odors of the smolt's native river are imprinted on its memory, to be recalled when it returns to spawn.
 

ADULT - Silvery hunters, adult wild salmon live one or more years at sea. Most populations follow lengthy migration routes to waters off southwestern Greenland where they grow rapidly on a diet of crustaceans and small fish. Other feeding grounds exist, such as waters surrounding the Faroe Islands north of Scotland, and some populations may stay closer to home rivers, such as those from the inner Bay of Fundy Rivers. Wild salmon that return after one year at sea are called GRILSE. Adult salmon return to home rivers, entering freshwater between April and November. Once in freshwater they stop feeding, living off accumulated fat reserves.
 

SPAWNING IN A REDD - In late fall the wild Atlantic salmon spawn. The female digs a 10-30cm/4-12 in. deep nest called a REDD in the gravel bottom of the stream. Her eggs and the milt from an adult male are released into the redd, the gravel replaced with additional tail thrusts. In some cases sexually mature male parr manage to fertilize a percentage of the eggs. In the painting parr are seen swimming nearby, looking for an opportunity. The female may lay 1,500 eggs or more for each kg./2.2 lb of body weight. - Thus a 12 pound female salmon will lay about 8,000 eggs, completing the life cycle.

Facts About Atlantic Salmon

• Wild Atlantic salmon can attain swimming speeds of up to 20 miles per hour.
   

• Wild Atlantic salmon can hurdle 12 foot (3.8 m) waterfalls.
   

• Wild Atlantic salmon can live to be 15 years old.
   

• Wild Atlantic salmon can survive for up to 22 months without eating when they return from the ocean to their birth rivers to spawn.
   

• Wild Atlantic salmon can swim more than 2,500 miles (4,000 km) to feeding grounds near Greenland and the Faroe Islands.
   

• Wild Atlantic salmon can weigh up to 83 pounds (38 kg).
   

• Wild Atlantic salmon females choose nest sites where the concentration of fine silt is low and dissolved oxygen high.
   

• Wild Atlantic salmon have spawned up to seven times.
   

• Wild Atlantic salmon were one of the earliest known art subjects.
   

• Wild Atlantic salmon will return to the almost exact spot where they hatched to spawn.
   

• Atlantic salmon, in Celtic lore, were believed to be endowed with secret knowledge.
   

• Atlantic salmon use their sense of smell to guide them near shore and as they ascend a river.
   

• No one is certain how salmon navigate at sea, but they may use the earth's magnetic field.