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 °C) 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 °C and were lowest between 8.0 and 15.5 °C, with larger fish tending to exhibit the greatest change in R R irrespective of the temperature combination. Energy losses resulting from R SDA were ~4% 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.