The influence of the freshwater environment and the biological characteristics of Atlantic salmon smolts on their subsequent marine survival

Ian Russell, Miran Aprahamian, Jon Barry, Ian Davidson, Peder Fiske, Anton Ibbotson, Richard Kennedy, Julian Maclean, Andrew Moore, Jaime Otero, Ted Potter, Christopher David Todd

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)
8 Downloads (Pure)

Abstract

Atlantic salmon have declined markedly in the past 20-30 years throughout their range. Much of the focus for this decline has been on increased mortality during the marine phase of the life cycle. However, marine mortality does not operate independently of factors acting in freshwater and the biological characteristics of smolts migrating to sea. Over recent decades, juvenile salmon in many rivers have grown faster and migrated to sea at a younger age, and thus typically smaller. This has shortened the generation time for many individuals, and may dampen the impact of increased marine mortality, assuming expected higher in-river survival prior to smolting is not outweighed by increased mortality of smaller smolts at sea. Over the same period, smolt run-timing across the geographic range has been occurring earlier, at a rate of almost three days per decade, on average. This has given rise to growing concerns about smolts potentially missing the optimum environmental migration “window”, the timing of which may also be changing. Contaminants and other factors operating in freshwater also impact on smolt quality with adverse consequences for their physiological readiness for life at sea. Given that managers have very limited ability to influence the broad scale factors limiting salmon survival at sea, it is vital that freshwater habitats are managed to both maximise smolt output and to minimise the impact of factors acting in freshwater which may compromise salmon once they migrate to sea.
Original languageEnglish
Pages (from-to)1563-1573
Number of pages11
JournalICES Journal of Marine Science
Volume69
Issue number9
Early online date27 Jan 2012
DOIs
Publication statusPublished - 2012

Keywords

  • Atlantic salmon
  • Biological characteristics
  • Climate change
  • Freshwater
  • Marine survival
  • Smolts

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