Migration patterns and navigation cues of Atlantic salmon post‐smolts migrating from 12 rivers through the coastal zones around the Irish Sea

Lilly, J. M. et al. (2024) Migration patterns and navigation cues of Atlantic salmon post‐smolts migrating from 12 rivers through the coastal zones around the Irish Sea. Journal of Fish Biology, 104(1), pp. 265-283. (doi: 10.1111/jfb.15591) (PMID:37843923)

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The freshwater phase of the first seaward migration of juvenile Atlantic salmon (Salmo salar) is relatively well understood when compared with our understanding of the marine phase of their migration. In 2021, 1008 wild and 60 ranched Atlantic salmon smolts were tagged with acoustic transmitters in 12 rivers in England, Scotland, Northern Ireland and Ireland. Large marine receiver arrays were deployed in the Irish Sea at two locations: at the transition of the Irish Sea into the North Atlantic between Ireland and Scotland, and between southern Scotland and Northern Ireland, to examine the early phase of the marine migration of Atlantic salmon smolts. After leaving their natal rivers’ post-smolt migration through the Irish Sea was rapid with minimum speeds ranging from 14.03 to 38.56 km.day-1 for Atlantic salmon smolts that entered the Irish Sea directly from their natal river, to 9.69 to 39.94 km.day-1 for Atlantic salmon smolts that entered the Irish Sea directly from their natal estuary. Population minimum migration success through the study area was strongly correlated with the distance of travel, populations further away from the point of entry to the open North Atlantic exhibited lower migration success. Post-smolts from different populations experienced different water temperatures on entering the North Atlantic. This was largely driven by the timing of their migration and may have significant consequences for feeding and ultimately survivorship. The influence of water currents on post-smolt movement was investigated using data from previously constructed numerical hydrodynamic models. Modelled water current data in the northern Irish Sea showed that post-smolts had a strong preference for migrating when the current direction was at around 283° (west-north-west) but did not migrate when exposed to strong currents in other directions. This is the most favourable direction for onward passage from the Irish Sea to the continental shelf edge current, a known accumulation point for migrating post-smolts. These results strongly indicate that post-smolts migrating through the coastal marine environment are: 1) not simply migrating by current following 2) engage in active directional swimming 3) have an intrinsic sense of their migration direction and 4) can use cues other than water current direction to orientate during this part of their migration.

Item Type:Articles
Additional Information:This study was funded by EU INTERREG VA Programme(Environment Theme), the Maritime Fisheries Fund, Salmon Scotland, the Atlantic Salmon Trust, the Environment Agency, Natural England, The Derwent Owners Association, United Utilities PLC, NatureScot the Nith District Salmon Fishery Board, the Holywood Trust, Dumfries and Galloway Council and the Department of Agriculture, Environment and Rural Affairs of Northern Ireland.
Glasgow Author(s) Enlighten ID:Lilly, Jessie Marie and Rodger, Dr Jessica and Elliott, Dr Sophie and Adams, Professor Colin and Honkanen, Dr Hannele and Bowman, Prof Adrian and Barry, Dr James and Boylan, Dr Patrick and Green, Amy and Bean, Professor Colin and Bailey, Dr David
Authors: Lilly, J. M., Honkanen, H. H., Rodger, J. R., del Villar, D., Boylan, P., Green, A., Pereiro, D., Wilkie, L., Kennedy, R., Barkley, A., Rosell, R., Ó Maoiléidigh, N., O’Neill, R., Waters, C., Cotter, D., Bailey, D., Roche, W., McGill, R., Barry, J., Beck, S. V., Henderson, J., Parke, D., Whoriskey, F. G., Shields, B., Ramsden, P., Walton, S., Fletcher, M., Whelan, K., Bean, C. W., Elliott, S., Bowman, A., and Adams, C. E.
College/School:College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
College of Science and Engineering > School of Mathematics and Statistics > Mathematics
Journal Name:Journal of Fish Biology
ISSN (Online):1095-8649
Published Online:16 October 2023
Copyright Holders:Copyright © 2023 The Authors
First Published:First published in Journal of Fish Biology 104(1):265-283
Publisher Policy:Reproduced under a Creative Commons license

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