Respiratory metabolism and swimming performance in growth hormone transgenic Atlantic salmon

We show that growth hormone enhanced transgenic salmon have a higher oxygen uptake during routine culture conditions and during forced swimming activity relative to similarly sized control fish. They also have a slightly higher critical oxygen level that limits oxygen uptake. However, they do not differ in regards to critical swimming speed. Growth hormone transgenic Atlantic salmon, Salmo salar, at 12-13 degrees C were an F-2 generation using eggs from a transgenic F-1 female and milt from a nontransgenic male. They grew two to three times faster than control fish throughout the study period. Under routine culture conditions, both 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/L in both groups of fish; critical oxygen uptake level was 6 mg/L in transgenic fish and 4 mg/L in control fish. During the 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.