Inferring Atlantic salmon post-smolt migration patterns using genetic assignment

Understanding migratory patterns is important for predicting and mitigating unwanted consequences of environmental change or anthropogenic challenges on vulnerable species. Wild Atlantic salmon undergo challenging migrations between freshwater and marine environments, and the numbers of salmon retur...

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Main Authors: A. C. Harvey, M. Quintela, K. A. Glover, Ø. Karlsen, R. Nilsen, Ø. Skaala, H. Sægrov, S. Kålås, S. Knutar, V. Wennevik
Format: Article
Language:English
Published: The Royal Society 2019-10-01
Series:Royal Society Open Science
Subjects:
Online Access:https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.190426
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author A. C. Harvey
M. Quintela
K. A. Glover
Ø. Karlsen
R. Nilsen
Ø. Skaala
H. Sægrov
S. Kålås
S. Knutar
V. Wennevik
author_facet A. C. Harvey
M. Quintela
K. A. Glover
Ø. Karlsen
R. Nilsen
Ø. Skaala
H. Sægrov
S. Kålås
S. Knutar
V. Wennevik
author_sort A. C. Harvey
collection DOAJ
description Understanding migratory patterns is important for predicting and mitigating unwanted consequences of environmental change or anthropogenic challenges on vulnerable species. Wild Atlantic salmon undergo challenging migrations between freshwater and marine environments, and the numbers of salmon returning to their natal rivers to reproduce have declined over several decades. Mortality from sea lice linked to fish farms within their seaward migration routes is proposed as a contributing factor to these declines. Here, we used 31 microsatellite markers to establish a genetic baseline for the main rivers in the Hardangerfjord, western Norway. Mixed stock analysis was used to assign Atlantic salmon post-smolts caught in trawls in 2013–2017 back to regional reporting units. Analyses demonstrated that individuals originating from rivers located in the inner region of the fjord arrived at the outer fjord later than individuals from middle and outer fjord rivers. Therefore, as post-smolts originating from inner rivers also have to migrate longer distances to exit the fjord, these data suggest that inner fjord populations are more likely to be at risk of mortality through aquaculture-produced sea lice, and other natural factors such as predation, than middle or outer fjord populations with earlier exit times and shorter journeys. These results will be used to calibrate models estimating mortality from sea lice on wild salmon for the regulation of the Norwegian aquaculture industry.
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spelling doaj.art-4e6dea31709a4da395e7af109e9e40fd2022-12-22T00:30:47ZengThe Royal SocietyRoyal Society Open Science2054-57032019-10-0161010.1098/rsos.190426190426Inferring Atlantic salmon post-smolt migration patterns using genetic assignmentA. C. HarveyM. QuintelaK. A. GloverØ. KarlsenR. NilsenØ. SkaalaH. SægrovS. KålåsS. KnutarV. WennevikUnderstanding migratory patterns is important for predicting and mitigating unwanted consequences of environmental change or anthropogenic challenges on vulnerable species. Wild Atlantic salmon undergo challenging migrations between freshwater and marine environments, and the numbers of salmon returning to their natal rivers to reproduce have declined over several decades. Mortality from sea lice linked to fish farms within their seaward migration routes is proposed as a contributing factor to these declines. Here, we used 31 microsatellite markers to establish a genetic baseline for the main rivers in the Hardangerfjord, western Norway. Mixed stock analysis was used to assign Atlantic salmon post-smolts caught in trawls in 2013–2017 back to regional reporting units. Analyses demonstrated that individuals originating from rivers located in the inner region of the fjord arrived at the outer fjord later than individuals from middle and outer fjord rivers. Therefore, as post-smolts originating from inner rivers also have to migrate longer distances to exit the fjord, these data suggest that inner fjord populations are more likely to be at risk of mortality through aquaculture-produced sea lice, and other natural factors such as predation, than middle or outer fjord populations with earlier exit times and shorter journeys. These results will be used to calibrate models estimating mortality from sea lice on wild salmon for the regulation of the Norwegian aquaculture industry.https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.190426aquaculturemanagementgeneticssalmon licesalmonidmigration
spellingShingle A. C. Harvey
M. Quintela
K. A. Glover
Ø. Karlsen
R. Nilsen
Ø. Skaala
H. Sægrov
S. Kålås
S. Knutar
V. Wennevik
Inferring Atlantic salmon post-smolt migration patterns using genetic assignment
Royal Society Open Science
aquaculture
management
genetics
salmon lice
salmonid
migration
title Inferring Atlantic salmon post-smolt migration patterns using genetic assignment
title_full Inferring Atlantic salmon post-smolt migration patterns using genetic assignment
title_fullStr Inferring Atlantic salmon post-smolt migration patterns using genetic assignment
title_full_unstemmed Inferring Atlantic salmon post-smolt migration patterns using genetic assignment
title_short Inferring Atlantic salmon post-smolt migration patterns using genetic assignment
title_sort inferring atlantic salmon post smolt migration patterns using genetic assignment
topic aquaculture
management
genetics
salmon lice
salmonid
migration
url https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.190426
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