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Zhang Y.,University of British Columbia | Timmerhaus G.,Nofima AS | Anttila K.,University of Turku | Mauduit F.,University of Western Brittany | And 8 more authors.
Aquaculture | Year: 2016

Commercially selective breeding of Atlantic salmon (Salmo salar) primarily for rapid growth may compromise cardiorespiratory robustness and its related phenotypes. Therefore, a suite of respiratory indices was used to evaluate aerobic capacity and hypoxia tolerance to test the hypothesis that exercise training can improve the athletic robustness in both domesticated and wild strains of Atlantic salmon, but with the domesticated strain having a less cardiorespiratory plasticity and a lower athletic robustness than the wild strain. We also tested a second hypothesis that a constant acceleration screening protocol should segregate fish according to athletic robustness based on their swimming ability. These hypotheses were tested with parr from Bolaks (domesticated) and Lærdal (wild) strains of Atlantic salmon that were reared under identical hatchery conditions. After screening into either inferior (bottom 20%) or superior (top 20%) swimmers, the four groups of fish (two strains and two swimming performance levels) either were given an 18-day exercise-training regime (an incremental water current of 2.0-2.8 fork lengths s-1), or were maintained at the control water current (0.5 fork lengths s-1) for 18 days. Subsequently, fish were sampled for metabolic enzyme analysis in red and white swimming muscles (citrate synthase, CS, and lactate dehydrogenase, LDH; n = 15 from each group) and their individual respiratory capacities were comprehensively assessed by measuring the standard metabolic rate (SMR), maximum rate of oxygen uptake (O2max), absolute aerobic scope (AAS), factorial aerobic scope (FAS), excess post-exercise oxygen consumption (EPOC), critical oxygen level (O2crit) and incipient lethal oxygen saturation (ILOS). Contrary to our expectations, the inferior and superior swimmers were indistinguishable in either strain and these data were pooled. While exercise training produced several tangible benefits for the wild fish, it produced very few for the domesticated fish. For example, the wild strain, but not the domesticated strain, had a significantly higher O2max, AAS and EPOC as a result of training. Also, CS activity in red muscle increased after training to a larger extent in the wild strain than in the domesticated strain. When compared with the wild strain, the domesticated strain had a significantly lower O2max, AAS, FAS and CS activity in white muscle. Thus, the domesticated strain appeared to be athletically less robust than the wild strain. These results imply that approximately ten generations of selective breeding for rapid growth in commercial aquaculture have reduced the overall athletic robustness of domesticated salmon as compared to their wild conspecifics, and given the success in improving athletic robustness of the wild strain, it still remains to be seen whether an exercise training protocol can be developed that will provide benefits to the salmon aquaculture industry. Statement of relevance: This manuscript fits perfectly with the scope of aquaculture. We address the possibility that the Norwegian Atlantic salmon (Salmo salar) breeding program that extensively focuses on commercial benefits traits may be compromising the cardiorespiratory system, which may contribute to the mortality of smolts after seawater transfer. We hypothesized that a combination of exercise-screening and exercise-training protocols could select for superior cardiorespiratory performance. This hypothesis was tested by comparing domesticated and wild Norwegian Atlantic salmon strains, and using comprehensive measurements of athletic and hypoxia performance in individual fish.We believe this paper will be of specific interest to aquaculture professionals who are seeking the enhanced husbandry approaches for achieving higher survival rate over seawater transfer as well as general physiologists. To our knowledge our study is the first to comprehensively illustrate athleticism of domesticated Atlantic salmon from biochemical and cardiorespiratory system levels. Furthermore, we believe this is the first study to show the promising results of enhancing cardiorespiratory system of domesticated Atlantic salmon strain in a hatchery setting.We used a suite of respiratory indices to evaluate athletic robustness and hypoxia performance in individual fish. We discovered that a domesticated strain of Atlantic salmon demonstrated a reduced athleticism and less plasticity in response to a short exercise-training regime compared with a wild strain of Atlantic salmon. We conclude that commercial aquaculture practices may trade off the robustness of the cardiorespiratory system, but not to an extent of completely losing the potential of benefiting from exercise training. © 2016.

Mota V.C.,Wageningen University | Martins C.I.M.,University of Algarve | Martins C.I.M.,Marine Harvest ASA | Edinga E.H.,Wageningen University | And 2 more authors.
Aquacultural Engineering | Year: 2014

Little information is available on steroid concentrations in the rearing water of aquaculture systemsand whether they accumulate in recirculating aquaculture systems (RAS). Therefore this study aimedat determining (1) the concentrations and variation of cortisol and sex steroids in RAS, (2) the con-tribution of fish rearing conditions to steroid concentrations in seven commercial RAS. Each RAS wassampled twice at three different points: (1) make-up water; (2) influent and (3) effluent of the rearing unit. The results showed significant higher steroid concentrations in the influent and effluent whencompared with the make-up water. On average cortisol concentration was 15.7% higher in the efflu-ent when compared with the influent. Mean steroid concentrations in the rearing unit effluent varied between: 3.8-217.0 ng/L for cortisol, 3-12.5 ng/L for testosterone, 0.9-7.1 ng/L for 11-ketoteststerone and 1.8-12.8 ng/L for 17,20β-dihydroxypregn-4-en-3-one. Stocking density, Total Ammonia-Nitrogen con-centration and orthophosphate-P concentration (a measure of make-up water usage) showed a positivecorrelation with sex steroids in the water. The steroid concentrations from the present study were ordersof magnitude lower than initial estimations indicating a water treatment efficiency of >99%. The resultssuggest that an intensification of fish production through decrease of make-up water use and increaseof stocking density will lead to a build-up of steroids in the water. Although intensification is critical forthe economical success of RAS, this ultimately could affect fish performance as steroids accumulates in the water of RAS at levels that can potentially be detected by some fish species. © 2014 Elsevier B.V.

Castanheira M.F.,University of Algarve | Martinez Paramo S.,University of Algarve | Figueiredo F.,University of Algarve | Figueiredo F.,Troms Krakebolle AS | And 7 more authors.
Fish Physiology and Biochemistry | Year: 2016

Individual differences in behaviour and physiological responses to stress are associated with evolutionary adaptive variation and thus raw material for evolution. In farmed animals, the interest in consistent trait associations, i.e. coping styles, has increased dramatically over the last years. However, one of limitations of the available knowledge, regarding the temporal consistency, is that it refers always to short-term consistency (usually few weeks). The present study used an escape response during a net restraining test, previously shown to be an indicative of coping styles in seabream, to investigate long-term consistency of coping styles both over time and during different life history stages. Results showed both short-term (14 days) consistency and long-term (8 months) consistency of escape response. However, we did not found consistency in the same behaviour after sexual maturation when the restraining test was repeated 16, 22 and 23 months after the first test was performed. In conclusion, this study showed consistent behaviour traits in seabream when juveniles, and a loss of this behavioural traits when adults. Therefore, these results underline that adding a life story approach to data interpretation as an essential step forward towards coping styles foreground. Furthermore, a fine-tuning of aquaculture rearing strategies to adapt to different coping strategies may need to be adjusted differently at early stages of development and adults to improve the welfare of farmed fish. © 2016 Springer Science+Business Media Dordrecht

Mo T.A.,Norwegian Veterinary Institute | Gahr A.,Norwegian Veterinary Institute | Hansen H.,Norwegian Veterinary Institute | Hoel E.,Marine Harvest Norway | Oaland O.,Marine Harvest ASA
Journal of Fish Diseases | Year: 2014

One hundred farmed Atlantic salmon, Salmo salar L., were examined for the presence of nematodes by digestion of tissue in HCl-pepsin solution. All fish were sampled from one cage in a fish farm on the Norwegian south-west coast. Fifty harvest quality salmon, that is, salmon for human consumption (mean 5.4 kg, variation 3.0-7.6 kg), were sampled at the processing line while 50 salmon runts (mean 1.1 kg, variation 0.4-1.8 kg), discarded due to poor performance, were sampled from the discard bin after the grading station. Runts are individual fish with clear signs of poor performance over time and abnormal appearance and are thus not processed for human consumption. No nematodes were found in the musculature or viscera of the 50 harvest quality salmon. In total, 75 nematodes were found in 10 (20%) of the runts; 53 nematodes in the viscera and 22 in the musculature. Nematodes in the musculature were identified as Anisakis simplex (Rudolphi, 1809 det. Krabbe, 1878), while nematodes in the viscera were identified as A. simplex and Hysterothylacium aduncum (Rudolphi, 1802). © 2013 John Wiley & Sons Ltd.

Mota V.C.,Wageningen University | Mota V.C.,University of Algarve | Limbu P.,Wageningen University | Martins C.I.M.,University of Algarve | And 3 more authors.
Aquacultural Engineering | Year: 2015

One of the challenges that Recirculating Aquaculture Systems (RAS) are still facing is the risk that in RAS fish grow less than in flow-through systems due to the accumulation of substances originating from feed, fish or bacteria associated with the water re-use. The present study investigated whether RAS with high and low accumulation levels of these substances affect feed intake and growth of Nile tilapia Oreochromis niloticus, African catfish Clarias gariepinus, and European eel Anguilla Anguilla. One-hundred and twenty individuals of each species were used (start body weights: Nile tilapia 264.8 ± 8.3. g; African catfish 253.2 ± 2.1. g and European eel 66.6 ± 1.3. g). For a period of 39 days, growth and feed intake were compared between high and low accumulation RAS. HIGH accumulation RAS was designed for maximal accumulation of substances in the water by operating the system at nearly-closed conditions (30. L/kg feed/d), using mature biofilters and high feed loads; and (2) LOW accumulation RAS was designed to be a proxy for flow-through systems by operating at high water exchange rates (1500. L/kg feed/d), new biofilters and low feed load. HIGH accumulation RAS induced a reduction in feed intake (42%) and growth (83%) of Nile tilapia, as compared to systems that are a proxy for flow-through conditions. This effect was not observed in European eel and African catfish. The cause of this reduced feed intake and growth rate of Nile tilapia is still unclear and should be addressed in further studies. © 2015.

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