PHYSIOLOGICAL-CHANGES IN SKELETAL-MUSCLE BY MATURATION-SPAWNING OF NONMIGRATING FEMALE ATLANTIC SALMON, SALMO-SALAR

1. Physiological properties of epaxial muscle of non-migrating female Atlantic salmon (Salmo salar) were compared between non-spawning and spawning fish. 2. The rise in blood plasma vitellogenin, and liver and gonadal weights confirmed the maturation-spawning condition. 3. In the spawning females DNA, glycogen and acid proteinase activity were elevated per g wet weight of muscle, while protein and RNA content of the sarcoplasmic fraction and RNA of the myofibrillar fraction were diminished. 4. The data suggest that characteristic changes occur in skeletal muscle by the process of maturation and spawning, which are independent of the physical load of upstream migration.