Detrimental effects of recent ocean surface warming on growth condition of Atlantic salmon

Christopher D. Todd, Sarah L. Hughes, C. Tara Marshall, Julian C. Maclean, Michael E. Lonergan, E. Martin Biuw

Research output: Contribution to journalArticle

94 Citations (Scopus)

Abstract

Ocean climate impacts on survivorship and growth of Atlantic salmon are complex, but still poorly understood. Stock abundances have declined over the past three decades and 1992-2006 has seen widespread sea surface temperature (SST) warming of the NE Atlantic, including the foraging areas exploited by salmon of southern European origin. Salmon cease feeding on return migration, and here we express the final growth condition of year-classes of one-sea winter adults at, or just before, freshwater re-entry as the predicted weight at standard length. Two independent 14-year time series for a single river stock and for mixed, multiple stocks revealed almost identical temporal patterns in growth condition variation, and an overall trend decrease of 11-14% over the past decade. Growth condition has fallen as SST anomaly has risen, and for each year-class the midwinter (January) SST anomalies they experienced at sea correlated negatively with their final condition on migratory return during the subsequent summer months. Stored lipids are crucial for survival and for the prespawning provisioning of eggs in freshwater, and we show that under-weight individuals have disproportionately low reserves. The poorest condition fish (similar to 30% under-weight) returned with lipid stores reduced by similar to 80%. This study concurs with previous analyses of other North Atlantic top consumers (e.g. somatic condition of tuna, reproductive failure of seabirds) showing evidence of major, recent climate-driven changes in the eastern North Atlantic pelagic ecosystem, and the likely importance of bottom-up control processes. Because salmon abundances presently remain at historical lows, fecundity of recent year-classes will have been increasingly compromised. Measures of year-class growth condition should therefore be incorporated in the analysis and setting of numerical spawning escapements for threatened stocks, and conservation limits should be revised upwards conservatively during periods of excessive ocean climate warming.

Original languageEnglish
Pages (from-to)958-970
Number of pages13
JournalGlobal Change Biology
Volume14
Issue number5
Early online date12 Dec 2007
DOIs
Publication statusPublished - May 2008

Keywords

  • anomaly
  • Atlantic salmon
  • bottom-up control
  • condition factor
  • fecundity
  • lipid reserves
  • NAO
  • ocean warming
  • Salmo salar
  • spawning
  • SST
  • time series
  • escaped farmed Atlantic
  • post-smolt growth
  • North-Sea area
  • Salar L.
  • climate-change
  • survival
  • bonferroni
  • fisheries
  • postsmolts
  • migration

Cite this

Detrimental effects of recent ocean surface warming on growth condition of Atlantic salmon. / Todd, Christopher D.; Hughes, Sarah L.; Marshall, C. Tara; Maclean, Julian C.; Lonergan, Michael E.; Biuw, E. Martin.

In: Global Change Biology, Vol. 14, No. 5, 05.2008, p. 958-970.

Research output: Contribution to journalArticle

Todd, Christopher D. ; Hughes, Sarah L. ; Marshall, C. Tara ; Maclean, Julian C. ; Lonergan, Michael E. ; Biuw, E. Martin. / Detrimental effects of recent ocean surface warming on growth condition of Atlantic salmon. In: Global Change Biology. 2008 ; Vol. 14, No. 5. pp. 958-970.
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T1 - Detrimental effects of recent ocean surface warming on growth condition of Atlantic salmon

AU - Todd, Christopher D.

AU - Hughes, Sarah L.

AU - Marshall, C. Tara

AU - Maclean, Julian C.

AU - Lonergan, Michael E.

AU - Biuw, E. Martin

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N2 - Ocean climate impacts on survivorship and growth of Atlantic salmon are complex, but still poorly understood. Stock abundances have declined over the past three decades and 1992-2006 has seen widespread sea surface temperature (SST) warming of the NE Atlantic, including the foraging areas exploited by salmon of southern European origin. Salmon cease feeding on return migration, and here we express the final growth condition of year-classes of one-sea winter adults at, or just before, freshwater re-entry as the predicted weight at standard length. Two independent 14-year time series for a single river stock and for mixed, multiple stocks revealed almost identical temporal patterns in growth condition variation, and an overall trend decrease of 11-14% over the past decade. Growth condition has fallen as SST anomaly has risen, and for each year-class the midwinter (January) SST anomalies they experienced at sea correlated negatively with their final condition on migratory return during the subsequent summer months. Stored lipids are crucial for survival and for the prespawning provisioning of eggs in freshwater, and we show that under-weight individuals have disproportionately low reserves. The poorest condition fish (similar to 30% under-weight) returned with lipid stores reduced by similar to 80%. This study concurs with previous analyses of other North Atlantic top consumers (e.g. somatic condition of tuna, reproductive failure of seabirds) showing evidence of major, recent climate-driven changes in the eastern North Atlantic pelagic ecosystem, and the likely importance of bottom-up control processes. Because salmon abundances presently remain at historical lows, fecundity of recent year-classes will have been increasingly compromised. Measures of year-class growth condition should therefore be incorporated in the analysis and setting of numerical spawning escapements for threatened stocks, and conservation limits should be revised upwards conservatively during periods of excessive ocean climate warming.

AB - Ocean climate impacts on survivorship and growth of Atlantic salmon are complex, but still poorly understood. Stock abundances have declined over the past three decades and 1992-2006 has seen widespread sea surface temperature (SST) warming of the NE Atlantic, including the foraging areas exploited by salmon of southern European origin. Salmon cease feeding on return migration, and here we express the final growth condition of year-classes of one-sea winter adults at, or just before, freshwater re-entry as the predicted weight at standard length. Two independent 14-year time series for a single river stock and for mixed, multiple stocks revealed almost identical temporal patterns in growth condition variation, and an overall trend decrease of 11-14% over the past decade. Growth condition has fallen as SST anomaly has risen, and for each year-class the midwinter (January) SST anomalies they experienced at sea correlated negatively with their final condition on migratory return during the subsequent summer months. Stored lipids are crucial for survival and for the prespawning provisioning of eggs in freshwater, and we show that under-weight individuals have disproportionately low reserves. The poorest condition fish (similar to 30% under-weight) returned with lipid stores reduced by similar to 80%. This study concurs with previous analyses of other North Atlantic top consumers (e.g. somatic condition of tuna, reproductive failure of seabirds) showing evidence of major, recent climate-driven changes in the eastern North Atlantic pelagic ecosystem, and the likely importance of bottom-up control processes. Because salmon abundances presently remain at historical lows, fecundity of recent year-classes will have been increasingly compromised. Measures of year-class growth condition should therefore be incorporated in the analysis and setting of numerical spawning escapements for threatened stocks, and conservation limits should be revised upwards conservatively during periods of excessive ocean climate warming.

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KW - bottom-up control

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KW - NAO

KW - ocean warming

KW - Salmo salar

KW - spawning

KW - SST

KW - time series

KW - escaped farmed Atlantic

KW - post-smolt growth

KW - North-Sea area

KW - Salar L.

KW - climate-change

KW - survival

KW - bonferroni

KW - fisheries

KW - postsmolts

KW - migration

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DO - 10.1111/j.1365-2486.2007.01522.x

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VL - 14

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EP - 970

JO - Global Change Biology

JF - Global Change Biology

SN - 1354-1013

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ER -