Aspects of fish locomotion, exercise and growth, with special reference to Salmo salar
1. Aspects of the structure of the vertebrae and the geometrical arrangement of the myosepta were analysed in cod (Gadus morhua), mackerel (Scomber scombrus) and Atlantic salmon (Salmo salar) for different parts of the body. The findings are discussed in relation to the mode of swimming of these three species. 2. Experiments were carried out to investigate mechanical characteristics of the anaerobic swimming muscle of cod (Gadus morhua), including the effect of pulse shape on tetanic tension, the relationship between stimulation frequency and the height of tetanic tension and the force- velocity relationship. 3. Various effects of prolonged exercise on two age groups of salmon (S. salar) in seawater was investigated. Growth, both in length and weight was positively affected by the exercise regime. This effect was more pronounced in the younger fish which had spent one month in sea water as compared with fish which had spent 9 months in sea water. Food conversion efficiency was positively affected by the exercise regime up to a certain optimum swimming speed. The condition factor was reduced by exercise in the younger age group of salmon but in the older group no effect could be demonstrated. 4. The effect of prolonged exercise in salmon on various body constituents was investigated, including heart and liver weight, muscle metabolites and blood parameters related to oxygen transport. The implication of the changes, with emphasis on the type of metabolism occurring in fish during prolonged exercise are discussed. 5. Experiments were performed to investigate the time course over which changes in the body constituents during prolonged exercise take place. 6. The effect of vigorous exercise on blood constituents and muscle metabolites of trained and tank-rested salmon were investigated. It was found that trained salmon had a higher stamina, greater tolerance to lactic acid and a faster rate of recovery, with respect to most of the parameters analysed, than tank-rested salmon. 7. Mortalities after vigorous exercise were higher in trained than tank-rested salmon. Factors affecting mortality in fish following exhausting exercise are discussed. 8. The application of the results from the growth experiments to improved productivity in salmon farms is discussed.