The adaptive significance of lakeward migrations by juvenile Atlantic salmon, Salmo salar L.

Hutchings, Jeffrey Alexander (1985) The adaptive significance of lakeward migrations by juvenile Atlantic salmon, Salmo salar L. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (18MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

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.

Actions (login required)

View Item