Risk taking and downstream migration in hatchery reared Atlantic salmon (Salmo salar) smolt

• Main Author: Finn, Fia
• Format: Bachelor Thesis
• Language: English
• Published: UmeÃ¥ universitet, Institutionen för ekologi, miljö och geovetenskap 2015
• Subjects: Behavior; migration; risk taking; boldness; Salmo salar; Ecology; Ekologi; Atlantic salmon
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-108496

Individual variation and limited plasticity in behavior are factors that have been shown to shape populations and determine how well individuals are doing in different stages of life. When salmon transform from parr to smolt and start the migration out to sea many factors together make an individual successful. The hypothesis of this study was that the boldness of individual smolt (1 and 2 year olds) is correlated to their inclination to migrate downstream. The study also investigated difference in boldness and migration tendency between 1- and two year old smolt. Today, some hatcheries release smolt as both one and two year old and it is important to know whether there is any difference in behavior and migration intensity between age classes in order to make stocking programs more effective. To determine if the individuals differed in boldness, and/or displayed a bold behavioral type, two assays were performed in different contexts (novel environment and simulated predatory attack). Downstream migratory intensity was, after behavior assays, quantified in an artificial stream. I found that: i) the one year old smolts tended to be bolder in a predatory response assay than two year old smolt, ii) one year old smolts migrated less in the artificial stream compared to two year old smolt. Being bolder can have an effect on several aspects connected to fitness in the salmon life cycle and could affect the survival of a smolt migrating out to sea, even though no correlations to inclination to downstream migration were found in this study.Â