Diel migration patterns of Atlantic salmon smolts with particular reference to the absence of crepuscular migration

Ibbotson, A. T.; Beaumont, W. R. C.; Pinder, A.; Welton, S.; Ladle, M.. 2006 Diel migration patterns of Atlantic salmon smolts with particular reference to the absence of crepuscular migration. Ecology of Freshwater Fish, 15. 544-551. 10.1111/j.1600-0633.2006.00194.x

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Abstract/Summary

Abstract – The real-time diel pattern of Atlantic salmon smolt migration was observed for 8 years using automatic resistivity counters verified by video surveillance. A clear dominant nocturnal migration was demonstrated early in the migration period, later becoming increasingly diurnal, until rates became approximately equal at day and night. Migration patterns were related to water temperature, such that when mean daily temperatures were below 12 °C, hourly rates of migration were significantly lower during the day than at night. When daily mean temperatures exceeded 12 °C, there was no significant difference between diurnal and nocturnal migration rates. Migration patterns showed a distinct suppression of migration at dawn and dusk throughout the migration period. It is hypothesised that this behaviour is an active decision and/or an adaptive strategy either to take advantage of increased food in the form of invertebrate drift or to reduce predation risk from actively feeding piscivores or both.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1111/j.1600-0633.2006.00194.x
Programmes:	CEH Programmes pre-2009 publications > Water
UKCEH and CEH Sections/Science Areas:	_ River Ecology
ISSN:	0906-6691
Additional Keywords:	Atlantic salmon, Salmo salar, smolts, diel migration patterns, crepuscular
NORA Subject Terms:	Ecology and Environment
Date made live:	02 May 2008 10:25 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/2874

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