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

• Main Authors: Davidsen, Jan Grimsrud, Plantalech Manel-la, Nuria, Thorstad, E.B, Rikardsen, Audun H., Økland, F., Sivertsgård, Rolf, Finstad, B, McKinley, R.S, Diserud, O. H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Blackwell Publishing 2008
• Subjects: VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Other fisheries disciplines: 929; VDP::Mathematics and natural science: 400::Zoology and botany: 480::Marine biology: 497; acoustic telemetry; behaviour; salmonid; vertical movement; Norway; Atlantic salmon; Salmo salar
• Online Access: https://hdl.handle.net/10037/2227

Dette er forfatternes aksepterte versjon. This is the author’s final accepted manuscript. 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.