A Biochemical Study of Coho Salmon (Oncorhynchus kisutch) Maturing Sexually in an Aquarium

Migrating coho salmon (Oncorhynchus kisutch) captured at a point near their entry into fresh water underwent sexual maturation when confined in an aquarium. Maturation was characterized by the development of secondary sex characters in the male and a considerable increase in the proportion of the body weight that could be accounted for as eggs in the female. Fish were sacrificed at intervals over the maturation period. Analyses of skeletal muscle, lateral line muscle, kidney, liver, heart, milt and roe for fat, protein and water, and skeletal muscle for sodium and potassium were made. Blood was analysed for total protein, non-protein nitrogen, amino acids, glucose, sodium and potassium. With some exceptions, the changes observed exhibited the same general trends as have been found in fish migrating under natural conditions. The extent of the changes, however, was considerably less.Respiratory rates and glycolytic activities of the tissues analysed were also determined. No significant change in these measu...