Recapture rates of hatchery-reared Atlantic salmon ( Salmo salar) related to smolt development and time of release

• Published in: Aquaculture Vol. 118; no. 3; pp. 327 - 337
• Main Authors: Staurnes, M., Lysfjord, G., Hansen, L.P., Heggberget, T.G.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.12.1993; Elsevier Science; Elsevier Sequoia S.A
• Subjects: AGUA DE MAR; Animal aquaculture; Animal productions; ANIMALES JOVENES; Aquaculture; Biological and medical sciences; BODY CONDITION; Brackish; COLOR; COLOUR; CONDICION CORPORAL; COULEUR; EAU DE MER; ETAT CORPOREL; Fish; FISH CULTURE; Freshwater; Fundamental and applied biological sciences. Psychology; JEUNE ANIMAL; Marine; NORUEGA; NORVEGE; NORWAY; PISCICULTURA; PISCICULTURE; SALINIDAD; SALINITE; SALINITY; SALMO SALAR; SALT TOLERANCE; SEA WATER; SUPERVIVENCIA; SURVIE; SURVIVAL; TOLERANCE AU SEL; TOLERANCIA A LA SAL; Vertebrate aquaculture; YOUNG ANIMALS; Norway; River Ingdalselva; Physiological condition; Farming animal; Enzyme; Salmo salar; Osmoregulation; Tolerance; K; Animal introduction; Survival; Blood plasma; Salinity; Marine environment; Restocking; Smoltification; Vertebrata; Na; Pisces; Chlorides; Development; Hydrolases; exchanging ATPase
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/0044-8486(93)90467-D

Groups of 2-year-old Atlantic salmon ( Salmo salar) were released intermittently from the middle of April to late June 1986 into the River Ingdalselva in Central Norway. Their marine survival was estimated from return of tags. Their smolt status was assessed by morphological characterization (condition factor, smolt colouration), determination of gill Na K-ATPase activity and seawater tolerance challenge tests (survival in water of 40‰ salinity, mortality and ionic regulation in water of 33‰ salinity). Return rates were highest for fish released during a period from late April to mid-May which coincided with the time of highest seawater tolerance of smolts. Prior to this period the fish were incompletely smolted, and in late May–June the fish had poor seawater tolerance. Recapture rates were positively correlated to survival after 1, 3 or 6 days in water of 40‰ salinity, and negatively correlated to plasma Cl − concentration after 1 day in water of 33‰ salinity. There were no correlations between recapture rates and smolt colouration, condition factor, or gill Na K-ATPase activity. The condition factor decreased slowly during the experiment. A complete, silvery smolt colouration was not attained until late May, whereas gill Na K-ATPase activity remained high until mid-June when recapture rates were low.