A1 Journal article (refereed)
Warming temperatures and ectoparasitic sea lice impair internal organs in juvenile Atlantic salmon (2021)

Medcalf, K. E., Hutchings, J. A., Fast, M. D., Kuparinen, A., & Godwin, S. C. (2021). Warming temperatures and ectoparasitic sea lice impair internal organs in juvenile Atlantic salmon. Marine Ecology Progress Series, 660, 161-169. https://doi.org/10.3354/meps13610

JYU authors or editors

Publication details

All authors or editorsMedcalf, Kate E.; Hutchings, Jeffrey A.; Fast, Mark D.; Kuparinen, Anna; Godwin, Sean C.

Journal or seriesMarine Ecology Progress Series



Publication year2021


Pages range161-169


Publication countryGermany

Publication languageEnglish


Publication open accessOpenly available

Publication channel open accessPartially open access channel

Publication is parallel published (JYX)https://jyx.jyu.fi/handle/123456789/75018


As a consequence of climate change and open net-pen salmon farming, wild Atlantic salmon Salmo salar are increasingly likely to encounter elevated temperatures and parasite abundances during their early marine migration. Such stressors can compromise fitness by diminishing liver energy stores and impairing cardiac muscle. To assess whether temperature and infestation by salmon lice Lepeophtheirus salmonis are important correlates of liver energy stores and cardiac muscle performance in juvenile salmon, we experimentally infested fish at 3 abundances of louse infestation (zero, low, and high) and 5 temperatures (10, 13, 16, 19, and 22°C). At the end of the experiment (i.e. when sea lice reached adulthood), we calculated the percent dry weight of the liver (%DWL; a proxy for liver energy stores) and cardiosomatic index (CSI; a proxy for cardiac muscle performance) of each fish and fitted 5 linear mixed-effects models to both of these responses. For both %DWL and CSI, the best-supported model included additive fixed effects for both infestation level and temperature. Our top models predicted that, relative to zero infestation, high infestation reduces %DWL by 5.7% (95% CI: 5.3-6.2%) and increases CSI by 15.9% (14.4-18.0%), and low infestation reduces %DWL by 2.6% (2.2-3.0%) and increases CSI by 7.8% (6.7-10.0%). Our work suggests that stressors associated with ocean warming and coastal salmon aquaculture can compromise wild salmon fitness through the impairment of vital organs.

Keywordsfish culturesalmonclimate changestemperaturewarmingphysiological effectsparasitismparasitesbranchiura

Free keywordsclimate change; aquaculture; salmon farms; liver; heart; cardiosomatic index; Lepeophtheirus salmonis; hepatosomatic index

Contributing organizations

Related projects

Ministry reportingYes

Reporting Year2021

JUFO rating1

Last updated on 2024-22-04 at 20:59