Combining acoustic telemetry with a mechanistic model to investigate characteristics unique to successful Atlantic salmon smolt migrants through a standing body of water

Lilly, J., Honkanen, H., McCallum, J. M., Newton, M., Bailey, D. M. and Adams, C. E. (2022) Combining acoustic telemetry with a mechanistic model to investigate characteristics unique to successful Atlantic salmon smolt migrants through a standing body of water. Environmental Biology of Fishes, 105(12), pp. 2045-2063. (doi: 10.1007/s10641-021-01172-x)

Abstract

The Atlantic salmon, Salmo salar Linnaeus 1758, is a charismatic, anadromous species that has faced dramatic declines throughout its range. There is currently a lack of information on the effect of free-standing bodies of water on a key life event, sea migration, for the species. This study extends our understanding in this area by combining acoustic telemetry with a correlated random walk model to try to examine potential morphological and behavioural factors that differentiate successful from unsuccessful migrants through Scotland’s largest lake. Consistent with other studies, we found that smolts experienced a high rate of mortality in the lake (~ 43%), with approximately 14% potentially predated upon by birds and 4% by Northern pike. Migration speed in the lake was slow (the mean minimum movement speed between centres of activity was 0.13 m/s), and pathways frequently deviated away from the outlet river. There was no evidence of a morphological or behavioural trait or migratory pathway that distinguished successful from unsuccessful smolts. This suggests that migration movement direction in the main body of Loch Lomond appeared to be random. This was further supported by the output of a correlated random walk model which closely resembled the pathway and migration speed and distance patterns displayed by successful migrants. However, once successful smolts came within ~2 km of the lake exit, a high proportion remained in this region prior to entering the River Leven. We suggest that this “goldilocks zone” is where directional cues become apparent to migrating fish. Future studies should combine random walk models with environmental variables to determine if external factors are driving the apparently random movement patterns exhibited by smolts in lakes.

• Item Type: Articles
• Additional Information: This work was part of the SeaMonitor project funded by the European Union INTERREG VA Programme award number IVA5060; additional funding was provided by the Atlantic Salmon Trust.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Lilly, Jessie Marie and Adams, Professor Colin and Newton, Dr Matthew and Bailey, Dr David and Honkanen, Dr Hannele
• Authors: Lilly, J., Honkanen, H., McCallum, J. M., Newton, M., Bailey, D. M., and Adams, C. E.
• College/School: College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Journal Name: Environmental Biology of Fishes
• Publisher: Springer
• ISSN: 0378-1909
• ISSN (Online): 1573-5133
• Published Online: 23 October 2021
• Copyright Holders: Copyright © 2021 The Authors
• First Published: First published in Environmental Biology of Fishes 105(12): 2045-2063
• Publisher Policy: Reproduced under a Creative Commons License