Respiratory metabolism and swimming performance in growth hormone transgenic Atlantic salmon

In 1996, F2 growth hormone-transgenic Atlantic salmon (Salmo salar) were produced using eggs from a transgenic F1 female and milt from a non-transgenic male. Non-transgenic control fish were also produced from the same stock. All fish were reared at 12-13°C and fed a commercial pelleted ration for 194 days. Growth rate of transgenic fish was 3 times faster than that of control fish throughout the study period. Under routine culture conditions, transgenic and control fish exhibited a diurnal cycle in oxygen uptake. However, oxygen uptake of transgenic fish was 1.7 times that of control fish at all times of the day. Oxygen uptake was independent of oxygen concentration above 10 mg/litre in both groups of fish; critical oxygen uptake level was 6 mg/litre in transgenic fish and 4 mg/litre in control fish. During oxygen decrease, transgenic fish and control fish lost equilibrium at the same low oxygen concentration levels. In the swim tunnel, oxygen uptake of transgenic fish was 1.6 times that of control fish at all swimming speeds. Critical swimming speeds did not differ between transgenic and control fish and were similar to literature values for salmonids.