Relationships between Na+, K+-ATPase, sialic acid content and fluidity in rainbow trout density-separated erythrocytes

Smolt of anadromous Arctic charr Sahelinus alpinus (L.) migrating from Storvatn, northern Norway, had a similar feeding intensity as resident Arctic charr from the benthic- and pelagic zone in early summer in fresh water. While smolts fed mostly on surface insects, however, resident Arctic charr had a more broader diet consisting mostly of chironomids, Bosmina sp., benthic prey and surface insects. This indicates that Arctic charr smolts have adopted a surface oriented feeding behaviour prior to their sea migration.