High prevalence of straying in a wild brown trout (Salmo trutta) population in a fjord system

Kristi Kaello, Henrik Baktoft, Martin Lykke Kristensen, Kim Birnie-Gauvin, Kim Aarestrup*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Natal homing is a prevalent life-history strategy among salmonids. However, not all individuals return to their natal river, a behaviour known as straying. In this study, we investigated the prevalence of straying and its connection to different life-history characteristics in an anadromous brown trout (Salmo trutta) population. In total, 21 538 juvenile out-migrating brown trout were tagged with Passive Integrated Transponder (PIT) tags in two years. Individuals were grouped according to their developmental status (parr, pre-smolt, and smolt) at the time of out-migration to investigate the effect of such life-history characteristic on the likelihood of straying. High number of anadromous brown trout (36%) were detected in non-natal rivers. Individuals spending longer time at sea were less likely to stray. Additionally, the likelihood of straying was dependent on the developmental status during out-migration, with parr having lower likelihood to stray compared to pre-smolt and smolt. However, the latter is further dependent on length and timing of juvenile out-migration. These results indicate that straying is an inherent part of this anadromous brown trout population and it is influenced by several life-history characteristics at different life stages. This may have significant implications to genetic structure within and between populations and to population dynamics.
Original languageEnglish
Article numberfsac079
JournalICES Journal of Marine Science
Issue number5
Pages (from-to)1539-1547
Number of pages9
Publication statusPublished - 2022


  • Dispersal
  • Natal homing
  • Salmonids
  • Sea trout
  • Straying


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