Hydrobiologia

, Volume 582, Issue 1, pp 35–42 | Cite as

Effects of salmon lice infection and salmon lice protection on fjord migrating Atlantic salmon and brown trout post-smolts

  • Rolf Sivertsgård
  • Eva B. Thorstad
  • Finn Økland
  • Bengt Finstad
  • Pål Arne Bjørn
  • Niels Jepsen
  • Trude Nordal
  • R. Scott McKinley
Fish Telemetry

Abstract

Effects of artificial salmon lice infection and pharmaceutical salmon lice prophylaxis on survival and rate of progression of Atlantic salmon (n = 72) and brown trout post-smolts (n = 72) during their fjord migration, were studied by telemetry. The infected groups were artificially exposed to infective salmon lice larvae in the laboratory immediately before release in the inner part of the fjord to simulate a naturally high infection pressure. Groups of infected Atlantic salmon (n = 20) and brown trout (n = 12) were also retained in the hatchery to control the infection intensity and lice development during the study period. Neither salmon lice infection nor pharmaceutical prophylaxis had any effects on survival and rate of progression of fjord migrating Atlantic salmon post-smolts compared to control fish. Atlantic salmon spent on average only 151.2 h (maximum 207.3 h) in passing the 80 km fjord system and had, thus, entered the ocean when the more pathogenic pre-adult and adult lice stages developed. The brown trout, in comparison to Atlantic salmon, remained to a larger extent than Atlantic salmon in the inner part of the fjord system. No effect of salmon lice infection, or protection, was found in brown trout during the first weeks of their fjord migration. Brown trout will, to a larger extent than Atlantic salmon, stay in the fjord areas when salmon lice infections reach the more pathogenic pre-adult and adult stages. In contrast to Atlantic salmon, they will thereby possess the practical capability of returning to freshwater when encountering severe salmon lice attacks.

Keywords

Salmo salar Salmo trutta Telemetry Salmon lice Migration Aquaculture 

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Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • Rolf Sivertsgård
    • 1
  • Eva B. Thorstad
    • 2
  • Finn Økland
    • 2
  • Bengt Finstad
    • 2
  • Pål Arne Bjørn
    • 3
  • Niels Jepsen
    • 4
  • Trude Nordal
    • 2
  • R. Scott McKinley
    • 5
  1. 1.Norwegian College of Fishery ScienceUniversity of TromsøTromsøNorway
  2. 2.Norwegian Institute for Nature Research (NINA)TrondheimNorway
  3. 3.Norwegian Institute of Fisheries and Aquaculture ResearchTromsøNorway
  4. 4.Department of Inland FisheriesDanish Institute for Fisheries ResearchSilkeborgDenmark
  5. 5.West Vancouver LaboratoryThe University of British ColumbiaVancouverCanada

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