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Body condition of returning Atlantic salmon Salmo salar L. correlates with scale δ13C and δ15N content deposited at the last marine foraging location

Body condition of returning Atlantic salmon Salmo salar L. correlates with scale δ13C and δ15N content deposited at the last marine foraging location
Body condition of returning Atlantic salmon Salmo salar L. correlates with scale δ13C and δ15N content deposited at the last marine foraging location
Patterns of feeding and growth of Atlantic salmon Salmo salar L. in the marine environment are critical to understanding how observed declines in recruitment may reflect warming or other oceanic drivers. The isotopic composition of scales can provide insight into differences in marine feeding location and possibly temperature regime. The authors used archived scale samples to measure δ13C and δ15N deposited in the scales of one sea-winter (1SW) salmon during their last season of growth at sea before they returned to five Irish rivers. δ13C values were related statistically to observed salmon body condition (Fulton’s K), and fish with higher δ13C values tended to show significantly better condition. In contrast, δ15N values were negatively related to body condition. There was no important effect on condition of length at smolt migration, and the effect of duration of marine residence varied among rivers. It is likely that δ13C values partly reflected ambient ocean temperature and recent marine feeding environment before return migration, such that the observed relationship between higher δ13C values and increased body condition may express an advantage for adult fish feeding in warmer, potentially closer, waters. If greater body condition influences fitness, then a changing temperature regime in the Northeast Atlantic may drive shifts in salmon survival and reproduction. This study provides evidence that there is spatial and trophic variation at sea between salmon from rivers of origin that are located relatively close to each other, with potential consequences for body condition and, consequently, fitness and life history; this suggests that salmon populations from geographically proximate rivers within regions may exhibit differential responses to ocean-scale climatic changes across the Northeast Atlantic.
0022-1112
Feeney, Rory
37c30886-f64c-45ca-ae95-6cc712ab37b9
Trueman, Clive N.
d00d3bd6-a47b-4d47-89ae-841c3d506205
Gargan, Patrick G.
e3dec31c-b359-494f-9bb7-db019e2d6aa5
Roche, William K.
a5135b2d-cab5-481b-887a-78611fa00bff
Shephard, Samuel
e93dd4a5-39f9-4913-a79b-804f5c81759e
Feeney, Rory
37c30886-f64c-45ca-ae95-6cc712ab37b9
Trueman, Clive N.
d00d3bd6-a47b-4d47-89ae-841c3d506205
Gargan, Patrick G.
e3dec31c-b359-494f-9bb7-db019e2d6aa5
Roche, William K.
a5135b2d-cab5-481b-887a-78611fa00bff
Shephard, Samuel
e93dd4a5-39f9-4913-a79b-804f5c81759e

Feeney, Rory, Trueman, Clive N., Gargan, Patrick G., Roche, William K. and Shephard, Samuel (2022) Body condition of returning Atlantic salmon Salmo salar L. correlates with scale δ13C and δ15N content deposited at the last marine foraging location. Journal of Fish Biology. (doi:10.1111/jfb.14968).

Record type: Article

Abstract

Patterns of feeding and growth of Atlantic salmon Salmo salar L. in the marine environment are critical to understanding how observed declines in recruitment may reflect warming or other oceanic drivers. The isotopic composition of scales can provide insight into differences in marine feeding location and possibly temperature regime. The authors used archived scale samples to measure δ13C and δ15N deposited in the scales of one sea-winter (1SW) salmon during their last season of growth at sea before they returned to five Irish rivers. δ13C values were related statistically to observed salmon body condition (Fulton’s K), and fish with higher δ13C values tended to show significantly better condition. In contrast, δ15N values were negatively related to body condition. There was no important effect on condition of length at smolt migration, and the effect of duration of marine residence varied among rivers. It is likely that δ13C values partly reflected ambient ocean temperature and recent marine feeding environment before return migration, such that the observed relationship between higher δ13C values and increased body condition may express an advantage for adult fish feeding in warmer, potentially closer, waters. If greater body condition influences fitness, then a changing temperature regime in the Northeast Atlantic may drive shifts in salmon survival and reproduction. This study provides evidence that there is spatial and trophic variation at sea between salmon from rivers of origin that are located relatively close to each other, with potential consequences for body condition and, consequently, fitness and life history; this suggests that salmon populations from geographically proximate rivers within regions may exhibit differential responses to ocean-scale climatic changes across the Northeast Atlantic.

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Body condition of 1SW salmon correlates with d13C and d15N_revise1 - Accepted Manuscript
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Accepted/In Press date: 29 November 2021
e-pub ahead of print date: 2 December 2021
Published date: 21 February 2022

Identifiers

Local EPrints ID: 456001
URI: http://eprints.soton.ac.uk/id/eprint/456001
ISSN: 0022-1112
PURE UUID: 8dc27b1e-0f4b-4304-be9a-ad0c0ba438b1
ORCID for Clive N. Trueman: ORCID iD orcid.org/0000-0002-4995-736X

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Date deposited: 12 Apr 2022 16:30
Last modified: 07 Jun 2024 04:01

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Contributors

Author: Rory Feeney
Author: Patrick G. Gargan
Author: William K. Roche
Author: Samuel Shephard

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