Relative to controls, GH-transgenic Atlantic salmon had a 29% larger
heart, 18% greatermass-specific cardiac output, 14% greater hemoglobin
concentration, 5–10% higher red muscle and heart aerobic enzyme activities, and 1.7–2.0-fold higher catecholamine levels, yet exhibited 18% lower metabolic scope and 9% lower critical swimming speed gill surface areawas not enhanced and that oxygen
transfer may have been limiting