Metabolic rate of pre-smolt growth-enhanced transgenic Atlantic salmon ( Salmo salar)

The rates of routine oxygen consumption of growth-enhanced transgenic Atlantic salmon were compared with that of non-transgenic salmon, over a pre-smolt body interval of 8–55 g to determine whether or not the transgenic salmon also expressed a greater metabolic rate. Routine oxygen consumption rates (mg O 2/h), inclusive of the heat increment associated with feeding, were 1.54- to 1.70-fold higher for transgenic fish compared to the controls. However, integrated over time from first feeding to smolt size, the transgenic salmon actually consumed 42% less total oxygen than the non-genetically modified controls to reach smolt size. In a post-absorptive state (24 h starvation), corresponding oxygen consumption rates of transgenic fish were 1.58- to 2.30-fold greater than that of regular salmon. The added cost to smolt producers for the short-term delivery of more water or oxygen to support the elevated metabolism of such growth-enhanced fish would appear to be justified in light of the benefits in reducing smolt production time.