| GH transgenic Atlantic salmon transgenic grew 3.6x faster than non-transgenic controls, and most aspects of their cardiorespiratory system were upregulated. For example, they had greater resting and post-stress catecholamine levels, higher post-stress haemoglobin concentrations, increased maximum heart performance, and elevated aerobic enzyme activities. However, they had a higher routine metabolic rate without a change in maximum metabolic rate (MO2max), resulting in a decreased metabolic scope, and subsequently a lowered critical swimming speed. Overall, this study supports the theory of symmorphosis, in that most aspects of the transgenic's cardiorespiratory system are upregulated to accommodate the additional demands of higher growth and/or activity. However, the transgenics MO2max appears to be limited by their gill surface area, which was not upregulated. Further, it provides information on their physiology that can be used to: (1) understand their needs in an aquacultural setting: and (2) infer the possible ecological consequences of their escape. |
