Changes in swimming depths of Atlantic salmon Salmo salar post-smolts relative to light intensity

Authors

  • J. G. Davidsen,

    Corresponding author
    1. * Norwegian College of Fishery Science, University of Tromsø, NO-9037 Tromsø, Norway, The University of British Columbia, Centre for Aquaculture and Environmental Research, 4160 Marine Drive West Vancouver, BC V7V 1N6, Canada and § Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway
    Search for more papers by this author
  • N. Plantalech Manel-la,

    1. * Norwegian College of Fishery Science, University of Tromsø, NO-9037 Tromsø, Norway, The University of British Columbia, Centre for Aquaculture and Environmental Research, 4160 Marine Drive West Vancouver, BC V7V 1N6, Canada and § Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway
    Search for more papers by this author
  • F. ØKland,

    1. * Norwegian College of Fishery Science, University of Tromsø, NO-9037 Tromsø, Norway, The University of British Columbia, Centre for Aquaculture and Environmental Research, 4160 Marine Drive West Vancouver, BC V7V 1N6, Canada and § Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway
    Search for more papers by this author
  • O. H. Diserud,

    1. * Norwegian College of Fishery Science, University of Tromsø, NO-9037 Tromsø, Norway, The University of British Columbia, Centre for Aquaculture and Environmental Research, 4160 Marine Drive West Vancouver, BC V7V 1N6, Canada and § Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway
    Search for more papers by this author
  • E. B. Thorstad,

    1. * Norwegian College of Fishery Science, University of Tromsø, NO-9037 Tromsø, Norway, The University of British Columbia, Centre for Aquaculture and Environmental Research, 4160 Marine Drive West Vancouver, BC V7V 1N6, Canada and § Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway
    Search for more papers by this author
  • B. Finstad,

    1. * Norwegian College of Fishery Science, University of Tromsø, NO-9037 Tromsø, Norway, The University of British Columbia, Centre for Aquaculture and Environmental Research, 4160 Marine Drive West Vancouver, BC V7V 1N6, Canada and § Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway
    Search for more papers by this author
  • R. Sivertsgård,

    1. * Norwegian College of Fishery Science, University of Tromsø, NO-9037 Tromsø, Norway, The University of British Columbia, Centre for Aquaculture and Environmental Research, 4160 Marine Drive West Vancouver, BC V7V 1N6, Canada and § Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway
    Search for more papers by this author
  • R. S. McKinley,

    1. * Norwegian College of Fishery Science, University of Tromsø, NO-9037 Tromsø, Norway, The University of British Columbia, Centre for Aquaculture and Environmental Research, 4160 Marine Drive West Vancouver, BC V7V 1N6, Canada and § Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway
    Search for more papers by this author
  • A. H. Rikardsen

    1. * Norwegian College of Fishery Science, University of Tromsø, NO-9037 Tromsø, Norway, The University of British Columbia, Centre for Aquaculture and Environmental Research, 4160 Marine Drive West Vancouver, BC V7V 1N6, Canada and § Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway
    Search for more papers by this author

†Tel.: +47 776 46960; fax: +47 776 46020; email: jan.davidsen@nfh.uit.no

Abstract

Eight hatchery-reared Atlantic salmon Salmo salar post-smolts, implanted with acoustic depth sensing transmitters and manually tracked for 5–12 h in the Hardangerfjord (Norway), spent most of their time (49–99%) at 1–3 m depth during the day, whereas four of seven fish tracked were found close (<0·5 m) to the surface at night, with a strong negative cross-correlation between general swimming depth and surface light intensity. Hence, the actual swimming depth of post-smolts during their early marine migration may depend on the light conditions, although the individual variation in vertical movement pattern was large. No cross-correlations were found between light intensity and swimming depth during daytime periods with rapid changes in light intensity, indicating that other factors than light intensity were important in initiating the irregular dives that were recorded down to 6·5 m depth.

Ancillary