Water temperature and dietary histidine affect cataract formation in Atlantic salmon (Salmo salar L.) diploid and triploid yearling smolt

F Sambraus,R Waagbø,A Thorsen,P G Fjelldal,T J Hansen,S C Remø,T O Nilsen,E M Hevrøy

doi:10.1111/jfd.12594

F Sambraus, R Waagbø + Show 6 more

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https://doi.org/10.1111/jfd.12594

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Abstract

The aim of the present study was to investigate cataract development in diploid (2N) and triploid (3N) Atlantic salmon smolts and post-smolts at two water temperatures (10 and 16°C) given diets with different histidine supplementation (LH, 10.4 and HH, 13.1gkg-1 ) before and after seawater transfer. In freshwater, a severe cataract outbreak was recorded in both ploidies reared at 16°C. The cataract score was significantly higher in triploids compared to diploids, and the severity was lower in both ploidies fed the HH diet. The cataract development at 10°C was minor. Low gill Na+ , K+ -ATPase activity in fish reared at 16°C before seawater transfer was followed by osmoregulatory stress with elevated plasma electrolyte concentrations and high mortality in sea water. Both diploids and triploids reared at 10°C developed cataracts during the seawater period, with higher severities in triploids than diploids and a reduced severity in the fish fed the HH diet. The findings of this study demonstrate the importance of environmental conditions in the husbandry of Atlantic salmon, and particularly triploids, with regard to smoltification and adjusted diets to mitigate cataract development in fresh and sea water.

Highlights

The use of sterile farmed salmon is currently being tested as a countermeasure to protect the genetics of wild salmon, as it has demonstrated that escaped farmed salmon hybridize with wild conspecifics (Glover et al 2012)
The present study demonstrated that triploid Atlantic salmon yearlings developed more severe cataracts at high temperatures and with insufficient dietary histidine from 7 weeks prior to thirteen weeks after seawater transfer
This study demonstrated that the smoltification status of Atlantic salmon reared high water temperature in the weeks before seawater transfer is altered compared to ones reared at moderate temperature

Summary

Introduction

The use of sterile farmed salmon is currently being tested as a countermeasure to protect the genetics of wild salmon, as it has demonstrated that escaped farmed salmon hybridize with wild conspecifics (Glover et al 2012). Triploidization is the induction of sterility and currently the only alternative to produce sterile salmon with regard to commercial demands (Piferrer et al 2009). Triploid salmon differ from diploids by containing fewer but larger cells in most organs that, dependent on cell shape, can result in a reduced cellular surface to volume ratio that represents the basis of physiological differences (Benfey 1999). Differences in gut morphology between diploid and triploid salmon suggest differences in utilization and metabolism between ploidies (Peruzzi, Hagen & Jobling 2015), and differences in the susceptibility to cataracts

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