ICES Journal of Marine Science: Journal du Conseil Advance Access originally published online on December 18, 2006
ICES Journal of Marine Science: Journal du Conseil 2007 64(2):386-393; doi:10.1093/icesjms/fsl029
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Differences in risks and consequences of salmon louse, Lepeophtheirus salmonis (Krøyer), infestation on sympatric populations of Atlantic salmon, brown trout, and Arctic charr within northern fjords
1 Norwegian Institute of Fisheries and Aquaculture Research, Breivika, N–9291 Tromsø, Norway
2 The Norwegian College of Fishery Science, University of Tromsø, N–9037 Tromsø, Norway
3 Norwegian Institute for Nature Research, Tungasletta 2, N–7485 Trondheim, Norway
4 University of British Columbia, West Vancouver Laboratory, BC, Canada VTV 1N6
5 Norwegian Institute for Nature Research, Polar Environmental Centre, N-9296 Tromsø, Norway
Correspondence to P. A. Bjørn: Tel: +47 77 629249; fax: +47 77 629100; e-mail: paal-arne.bjorn{at}fiskeriforskning.no
Bjørn, P-A., Finstad, B., Kristoffersen, R., Rikardsen, A. H., and McKinley, R. S. 2007. Differences in risks and consequences of salmon louse, Lepeophtheirus salmonis (Krøyer), infestation on sympatric populations of Atlantic salmon, brown trout, and Arctic charr within northern fjords. – ICES Journal of Marine Science, 64: 386–393.Differences in salmon louse (Lepeophtheirus salmonis) infestation on sympatric populations of fjord-migrating, Atlantic salmon post-smolts (Salmo salar), brown trout (Salmo trutta) (sea trout), and Arctic charr (Salvelinus alpinus) were studied in three fjords with fish-farming activity in northern Norway during the period June–August 2000. Atlantic salmon post-smolts were only captured in the fjords during late June and early July, and probably left them subsequently. No fish were infested with salmon lice. In contrast, brown trout and Arctic charr had similar infection patterns during their sampling periods, with very low prevalence and mean infection intensity during June (0–21% and 0–6 lice per fish, respectively), slightly increasing in July (8–70% and 6–12 lice per fish, respectively), and peaking in August (80–88% and 19–27 lice per fish, respectively). The chalimus stages dominated during June and July, with a few pre-adult and adult stages observed in July, and all stages were found frequently during August. The observations indicate that Atlantic salmon may have a mismatch between the time of louse infestation and their post-smolt fjord migration in northern fjords. In contrast, brown trout and Arctic charr feed within the fjords throughout summer and have a higher risk of harmful infestation in years with suitable environmental conditions for salmon louse development, especially in fish-farming areas. Arctic charr usually spend the shortest time at sea of the three species, and the salmon lice may not have time to develop to the adult stage on this species.
Keywords: anadromy, fish farming, life history, migration, post-smolt, salmonid, salmon lice
Received 10 February 2006; accepted 5 October 2006; advance access publication 18 December 2006.