The adaptive significance of lakeward migrations by juvenile Atlantic salmon, Salmo salar L.
Freshwater migratory patterns of juvenile Atlantic salmon, Salmo salar, were examined to (1) quantify parr movements into and out of lakes, (2) determine the importance of lakes to smolt production, and (3) identify mechanisms permitting the sympatry of anadromous and resident salmon. Counting fence...
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| Format: | Thesis |
| Language: | English |
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Memorial University of Newfoundland
1985
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| Online Access: | https://research.library.mun.ca/4104/ https://research.library.mun.ca/4104/1/Hutchings_JeffreyAlexander.pdf https://research.library.mun.ca/4104/2/Hutchings_JeffreyAlexander.pdf |
| Summary: | Freshwater migratory patterns of juvenile Atlantic salmon, Salmo salar, were examined to (1) quantify parr movements into and out of lakes, (2) determine the importance of lakes to smolt production, and (3) identify mechanisms permitting the sympatry of anadromous and resident salmon. Counting fences were maintained at the mouth of Wings Brook, Newfoundland, and at the outlets of its two associated lakes. There was a lake- and seaward movement of parr from early-May to late-September, intensifying over a 6-8 week period during spring when smolt emigrated from the lakes. Lacustrine parr returned to the stream following either maturation (usually males) or smoltification (predominantly females). Lakes contributed 87-100% of the system's smolt production, provided conditions for increased parr growth and survival, and represented important overwintering habitat. Lakeward migrations appear to be innately controlled but regulated by the environment. My observations support the hypothesis that co-occurring anadromous and resident S. salar represent phenotypic polymorphism within a single population. |
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