The evolution of freshwater races of the Atlantic salmon (Salmo salar L.) in eastern North America
T HE life cycle of the Atlantic salmon (Salmo salar L.) is typically divided between freshwater and marine environments. Spawning occurs in rivers and the juvenile salmon, known as parr, remain in this habitat for from 1 to 7 years before changing into smolts and migrating to the sea. Little is know...
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| Format: | Text |
| Language: | English |
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1958
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.567.4713 http://pubs.aina.ucalgary.ca/arctic/arctic11-2-86.pdf |
| Summary: | T HE life cycle of the Atlantic salmon (Salmo salar L.) is typically divided between freshwater and marine environments. Spawning occurs in rivers and the juvenile salmon, known as parr, remain in this habitat for from 1 to 7 years before changing into smolts and migrating to the sea. Little is known of the marine life of the salmon except that it usually occupies a period of from 1 to 3 years, during which growth is extremely rapid. Following this phase the fish return to the rivers of their origin, attain full sexual maturity, and spawn, thus completing the cycle. All Atlantic salmon do not conform to this pattern, however, and a number of forms, known as Ouananiche, Sebago salmon, landlocked salmon, etc., are recognized, which complete their life cycle entirely ’ in fresh water. These freshwater races are exceedingly widespread in eastern North Amer-ica. Jordan and Evermann (1896) recognized two types and, although they were indistinguishable morphologically, listed them as subspecies of the Atlantic salmon, Salmo salar sebago and Salmo salar ouananiche. Wilder (1947) was unable to find any morphological criterion for separating the Sebago salmon from the Atlantic salmon. The most obvious distinction between the Atlantic salmon and its freshwater races is that the latter do not migrate to sea at any stage in the life cycle, although in many in-stances they are not prevented from doing so by other than physiological barriers. Sebago salmon inhabit lakes that are distributed along the fringe of the presumed maximum extent of the Pleistocene glaciation in eastern North America. A population, now extinct, inhabited Lake Ontario until the be-ginning of this century (Huntsman, 1944). Other populations are found in |
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