Aspects of osmoregulation in families of early Atlantic salmon (Salmo salar) smolts exposed to seawater

• Main Author: Mackie, Paula Marie
• Other Authors: Wright, P.A., Ballantyne, J.S.
• Format: Thesis
• Language: English
• Published: University of Guelph 2004
• Subjects: families; Atlantic salmon; osmoregulate; smolts; seawater; cold conditions; Salmo salar
• Online Access: https://hdl.handle.net/10214/23496

I tested the hypothesis that families of Atlantic salmon vary in their ability to osmoregulate in seawater under cold conditions. Eleven families of Atlantic salmon 0+ smolts were transferred to seawater and sampled 0 h, 24 h, 96 h, and 30 days post transfer. Plasma osmolality levels were significantly different between the families at 24 h of seawater exposure. The family with the lowest osmolality also displayed the highest gill Na+, K+ ATPase activity. Gill mRNA expression of Na+, K+ ATPase [alpha]-subunit isoform [alpha]1b increased following seawater exposure, whereas the [alpha]1a isoform immediately decreased, but there was no significant difference between families. Taken together, the inter-family differences in osmoregulatory ability suggest a genetic basis for salinity tolerance in Atlantic salmon smolts. Furthermore, it appears that under cold conditions (4°C) gill Na+, K+ ATPase plays an important role in ion regulation.