Effects of dietary betaine and sodium chloride on seawater adaptation in atlatic salmon parr (Salmo salar L.)

Abstract 1. 1. Parr in freshwater were fed supplementary betaine (1.5%) and/or NaCI (10%) from 27 September to 21 October, then directly transferred to seawater. 2. 2. Dietary betaine resulted in a 5-fold increase in muscle betaine content, but had no significant effect on either growth, or the degree of iono/osmotic imbalance following transfer to seawater. 3. 3. NaCI reduced growth rate, but stimulated gill Na + -K + -ATPase activity, and significantly reduced the degree of osmotic stress following transfer to seawater.