Energy losses due to routine and feeding metabolism in young-of-the-year juvenile Atlantic cod (Gadus morhua)

We examined the effects of body size (3-13 cm total length) and temperature (4.5, 8.0, 12.0, and 15.5 degreesC) on routine (R-R) and feeding (R-SDA) energy losses by laboratory-reared, young-of-year juvenile Atlantic cod (Gadus morhua). The magnitude of the effect of temperature on R-R, expressed via the Q(10), was nonlinear. Q(10) values were greatest at temperatures between 4.5 and 8.0 degreesC and were lowest between 8.0 and 15.5 degreesC, with larger fish tending to exhibit the greatest change in R-R irrespective of the temperature combination. Energy losses resulting from R-SDA were similar to4% of consumed energy, a value less than half that estimated for larger, year-1+ juvenile cod fed similar-sized rations. Data from this and other studies were combined to generate an equation estimating routine energy loss at different temperatures and body sizes for cod. The equation describes R-R over the eight orders of magnitude difference in body size from young larvae to adults within a range of environmental temperatures experienced by this species on Georges Bank and other areas in the North Atlantic.