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The physiology of saltwater acclimation in large juvenile Atlantic salmon Salmo salar

Version 2 2024-06-03, 07:02
Version 1 2018-06-26, 14:06
journal contribution
posted on 2024-06-03, 07:02 authored by MS Brown, PL Jones, Jared TrompJared Tromp, CA van Rijn, RA Collins, Luis AfonsoLuis Afonso
The present study investigated the effects of transferring freshwater (FW) acclimated S. salar (678 g) that had been maintained under a constant photoperiod and thermal regime, into FW (salinity 0) and salt water (SW; salinity 35) on growth and physiological responses over a 28 day period. There were no mortalities observed throughout the study and no significant differences in mass or fork length between FW and SW groups after 28 days. Compared with fish transferred to FW, plasma osmolality and plasma chloride levels increased significantly in fish in SW by day 1. In the SW group, plasma chloride and osmolality had decreased significantly at day 14 when compared with day 1. Na+ -K+ -ATPase activity was significantly higher in SW compared with the FW group from day 7 and thereafter, but continued to increase until day 22. No differences in plasma cortisol and thyroxine were observed between FW and SW groups throughout the study. Plasma glucose significantly increased from day 1 to day 2 in SW but not in the FW group and levels were significantly reduced in SW compared with the FW group at day 28. Plasma cholesterol and triglyceride levels were significantly higher in FW at day 22 and day 14 to day 22, respectively, when compared with the SW group. In the SW group, plasma cholesterol and triglyceride levels did not change significantly throughout the study. The findings of this study suggest that large S. salar retained in FW maintain a high level of SW tolerance in the absence of photoperiod and thermal regimes necessary for smoltification, as demonstrated by 100% survival, unaffected growth performance, increased Na+ -K+ -ATPase activity and a capacity to regulate plasma chloride and osmolality for 28 days in the SW group.



Journal of Fish Biology






NORWAY, Univ Bergen, Bergen








Special Issue: Salmonid Smoltification, Selected papers from the Tenth International Workshop on Salmonid Smoltification, Bergen, Norway, 14–18 August 2017

Publication classification

C Journal article, C1 Refereed article in a scholarly journal

Copyright notice

2018, The Fisheries Society of the British Isles