The effect of fasting period on swimming performance, blood parameters and stress recovery in Atlantic salmon post smolts

Hvas, Malthe; Stien, Lars Helge; Oppedal, Frode

doi:10.1016/j.cbpa.2021.110913

Cited by 18 publications

(22 citation statements)

References 45 publications

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“…While losing weight the length increased over the 4-week fasting period. Similar continued length growth has previously been shown in food-deprived Atlantic salmon and indicates that vertebrae and muscle development may work independently of each other ( Einen et al, 1998 ; Hvas et al, 2021b , 2022 ). Furthermore, continued length increases could prepare fish for accelerated muscle growth when feed becomes available again and thereby help facilitate compensatory growth ( Ali et al, 2003 ).…”

Section: Discussionsupporting

confidence: 81%

“…Interestingly, the U crit was unaffected by the 4-week fasting period within both acclimation temperatures. In a separate study Atlantic salmon also maintained their full U crit over a 4-week fasting period at 12°C ( Hvas et al, 2021b ), and a similar result was therefore expected at 9°C owing to lower temperatures having a lesser impact on metabolic demands. However, an unaffected U crit at 18°C was surprising as this elevated temperature represents suboptimal conditions for growth and behavioural preferences in this species (e.g.…”

Section: Discussionmentioning

confidence: 76%

“…The ṀO 2 remained stable within each treatment group during 4 hours of sustained swimming, providing evidence for that swimming efforts indeed remained aerobic. If this was not the case, anaerobic metabolism would cause lactate to accumulate in muscles and blood since lactate clearance is slow in salmonids ( Hvas et al, 2021b ; Schulte et al, 1992 ). Furthermore, only 3 ATP are produced when glycogen is converted to lactate while 5 ATP are required to convert lactate back to glycogen ( Burgetz et al, 1998 ).…”

Section: Discussionmentioning

confidence: 99%

“…The physiological responses to extended fasting periods in Atlantic salmon have so far mainly been studied at the lower and mid ranges of their thermal niche. For instance, at 12°C Atlantic salmon gradually downregulate resting metabolic rates over a 4-week fasting period as an adaptive response to save energy, while still maintaining the ability to adequately respond and recover from acute stress ( Hvas et al, 2020 , 2021b ). Additionally, weight loss and changes in body composition during up to 12 weeks of fasting have been studied in winter conditions, showing a remarkable resilience to food deprivation at low temperatures ( Einen et al, 1998 ; Lie and Huse, 1992 ).…”

Section: Introductionmentioning

confidence: 99%

“…In Atlantic cod ( Gadus morhua ) fasted for 12 weeks, the U crit was indeed reduced due to impairment of anaerobic work ( Martínez et al, 2004 ). Although the U crit in Atlantic salmon remained unaffected after 4 weeks of fasting at 12°C ( Hvas et al, 2021b ), similar resilience to food deprivation is presumably not possible in warmer, less optimal environments. Moreover, it is unknown to what extent Atlantic salmon are able to downregulate metabolic demands at higher temperatures during fasting periods and how sustained swimming, CoT and U opt are affected.…”

Section: Introductionmentioning

confidence: 99%

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Swimming energetics of Atlantic salmon in relation to extended fasting at different temperatures

Hvas

2022

Conservation Physiology

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Predicted future warming of aquatic environments could make fish vulnerable to naturally occurring fasting periods during migration between feeding and spawning sites, as these endeavours become energetically more expensive. In this study, Atlantic salmon (Salmo salar) acclimated to midrange (9°C) or elevated suboptimal (18°C) temperatures were subjected to critical (Ucrit) and sustained (4 hours at 80% Ucrit) swimming trials before and after 4 weeks of fasting. Fasting caused weight losses of 7.3% and 8.3% at 9°C and 18°C, respectively. The Ucrit was unaffected by fasting, but higher at 18°C. Fatigue was associated with higher plasma cortisol, osmolality, Na+ and Cl− at 18°C, and ionic disturbances were higher in fasted fish. All fish completed the sustained swim trials while maintaining constant oxygen uptake rates (ṀO2), indicating strictly aerobic swimming efforts. At low swimming speeds ṀO2 was downregulated in fasted fish by 23.8% and 15.6% at 9°C and 18°C, respectively, likely as an adaptation to preserve resources. However, at higher speeds ṀO2 became similar to fed fish showing that maximum metabolic rates were maintained. The changes in ṀO2 lowered costs of transport and optimal swimming speeds in fasted fish at both temperatures, but these energetic alterations were smaller at 18°C while routine ṀO2 was 57% higher than at 9°C. As such, this study shows that Atlantic salmon maintain both glycolytic and aerobic swimming capacities after extended fasting, even at elevated suboptimal temperatures, and adaptive metabolic downregulation provides increased swimming efficiency in fasted fish. Although, improved swimming energetics were smaller when fasting at the higher temperature while metabolism becomes elevated. This could affect migration success in warming climates, especially when considering interactions with other costly activities such as coping with parasites obtained when passing aquaculture sites during seaward travel or gonad development while being voluntarily anorexic during upriver travel to spawning grounds.

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Section: Discussionsupporting

confidence: 81%

Section: Discussionmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Swimming energetics of Atlantic salmon in relation to extended fasting at different temperatures

Hvas

2022

Conservation Physiology

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Liver Glycogen as a Sensitive Indicator of Food Limitation in Delta Smelt

Dhayalan,

Tran,

Hung

et al. 2023

Estuaries and Coasts

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Assessing habitat quality is a major goal of conservationists and restoration practitioners, but to associate habitat quality with biomarkers of vagile animals, the biomarkers must respond rapidly. Here, we identified a biomarker capable of rapidly detecting food limitation in the imperiled Delta Smelt (Hypomesus transpacificus), a pelagic fish endemic to the San Francisco Estuary (SFE). We conducted an experiment with fed and unfed treatments of hatchery-raised, sub-adult Delta Smelt that were sampled at 12 time points: 0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 14, and 21 days. We then compared four biomarkers using Day 21 fish: RNA/DNA in liver, triglycerides in liver, glycogen in liver, and glycogen in muscle. Of the liver endpoints, glycogen had the largest difference between treatments at Day 21, so we compared it to muscle glycogen across all time points. Liver glycogen declined by 60% after 1 day of fasting and remained depressed in the fasting treatment across all subsequent time points. Muscle glycogen also responded rapidly, taking only 2 days to decline by 39% in the fasting treatment, but the difference was inconsistent across subsequent time points. When applied to hatchery-released Delta Smelt collected from the SFE, liver glycogen concentrations were less than half that of the fed hatchery fish, consistent with the hypothesis of food limitation in the wild, but also several other potential causes. This study highlights the utility of liver glycogen as an indicator of recent foraging success in Delta Smelt.

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Full compensatory growth before harvest and no impact on fish welfare in Atlantic salmon after an 8-week fasting period

et al. 2022

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The effect of fasting period on swimming performance, blood parameters and stress recovery in Atlantic salmon post smolts

Cited by 18 publications

References 45 publications

Swimming energetics of Atlantic salmon in relation to extended fasting at different temperatures

Swimming energetics of Atlantic salmon in relation to extended fasting at different temperatures

Liver Glycogen as a Sensitive Indicator of Food Limitation in Delta Smelt

Full compensatory growth before harvest and no impact on fish welfare in Atlantic salmon after an 8-week fasting period

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