The interaction between water currents and salmon swimming behaviour in sea cages.
Positioning of sea cages at sites with high water current velocities expose the fish to a largely unknown environmental challenge. In this study we observed the swimming behaviour of Atlantic salmon (Salmo salar L.) at a commercial farm with tidal currents altering between low, moderate and high velocities. At high current velocities the salmon switched from the traditional circular polarized group structure, seen at low and moderate current velocities, to a group structure where all fish kept stations at fixed positions swimming against the current. This type of group behaviour has not been described in sea cages previously. The structural changes could be explained by a preferred swimming speed of salmon spatially restricted in a cage in combination with a behavioural plasticity of the fish.
Institute of Marine Research, Matredal, Norway.
David
D
Johansson
Institute of Marine Research, Matredal, Norway; Department of Biology, University of Bergen, Bergen, Norway.
Frida
F
Laursen
Department of Biology, University of Bergen, Bergen, Norway.
Anders
A
Fernö
Institute of Marine Research, Matredal, Norway.
Jan Erik
JE
Fosseidengen
Sintef Fisheries and Aquaculture, Trondheim, Norway.
Pascal
P
Klebert
Institute of Marine Research, Matredal, Norway.
Lars Helge
LH
Stien
Institute of Marine Research, Matredal, Norway.
Tone
T
Vågseth
Institute of Marine Research, Matredal, Norway.
Frode
F
Oppedal
D000818:Animals; D001522:Behavior, Animal; D004784:Environmental Monitoring; D005398:Fisheries; D009792:Oceans and Seas; D012474:Salmon / Q000502:physiology*; D013550:Swimming; D014872:Water Movements