The effects of dietary NaCl supplement on hypo-osmoregulatory ability and sea water performance of Arctic charr (Salvelinus alpinus L.) smolts

• Published in: Aquaculture research Vol. 31; no. 10; pp. 737 - 743
• Main Authors: Staurnes, Magne, Finstad, Bengt
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.10.2000
• Subjects: Brackish; Freshwater; Marine; Salvelinus alpinus; Norway
• ISSN: 1355-557X; 1365-2109
• DOI: 10.1046/j.1365-2109.2000.00495.x

Groups of one‐year‐old smolts of Arctic charr (Salvelinus alpinus L.) reared under a simulated natural photoperiod were fed pelleted feed with a NaCl content of either 1.5% or 9.5% for 6 weeks before release in a river in northern Norway. There were no differences in growth before release between fish fed the two diets. Smolts fed the 9.5% NaCl diet had better hypo‐osmoregulatory ability than those fed the 1.5% diet, and a level of gill Na+‐K+‐ATPase activity that was several times higher. One of the two groups that had been fed the 9.5% NaCl diet had both a significantly higher recapture rate and growth in sea than the two groups fed the 1.5% NaCl diet, whereas this was not true for the other 9.5% NaCl diet group. The results indicate that a NaCl‐enriched diet could be used to ensure sufficient hypo‐osmoregulatory ability of charr smolts that would otherwise have insufficient regulatory ability.