CHANGES IN BLOOD AND SEMINAL PLASMA COMPOSITION OF THE MATURE SALMON (ONCORHYNCHUS-KETA) DURING ADAPTATION TO FRESHWATER

1. 1. Seminal plasma of the mature salmon Oncorhynchus keta, was analysed for major inorganic and organic constituents, and their changes accompanying freshwater adaptation were compared with those of the blood plasma. 2. 2. Potassium concentration of the seminal plasma exceeded greatly the plasma level, whereas sodium concentration and the osmolality were almost identical with those of the blood plasma. 3. 3. As compared with blood plasma, seminal plasma contained almost negligible amounts of glucose, cholesterol, protein and cortisol. 4. 4. Unlike the blood plasma, the osmolality of the seminal plasma calculated from sum of cations exceeded the measured value. 5. 5. On transfer from seawater to freshwater, marked decrease in the levels of sodium, chloride and osmolality was observed both in the blood plasma and in the seminal plasma, whereas the decrease was more marked in the seminal plasma than in the blood plasma. © 1979.