Carbohydrate and Amino Acid Metabolism in the Liver of Masu Salmon Oncorhynchus masou in the Early Period of Seawater Migration

Abstract

About 100,000 individuals of masu salmon Oncorhynchus masou were released into Ukai River in Noto Peninsula. Then the released fish were collected in the river and coastal zone of the peninsula, and the hepatic enzyme activities were determined to investigate the metabolic response in the liver during the migration from river to sea. The activities of amino acid degrading enzymes (alanine aminotransferase and aspartate aminotransferase) and gluconeogenic enzyme (fructose-1,6-diphosphatase) were significantly higher in the fish caught in the sea than in those caught in the river, whereas no remarkable difference in the lipogenic and glycolytic enzyme activities was found between the fish caught in the river and those caught in the sea. These results suggest that amino acid degradation and gluconeogenesis in the liver of masu salmon were enhanced in the early period of seawater migration.