Metabolic oxygen requirements of small, pleuronectid flatfish under simulated aquaculture conditions

The metabolic requirements of small, pleuronectid flatfish were determined by measuring routine oxygen consumption (ROC). ROC rates were measured using single-pass, flow-through respirometry tanks designed to simulate land-based aquaculture holding conditions. The influence of each test parameter was affected by temperature. Interactions between test parameters and oxygen consumption rate were significant according to ANOVA $(P < 0.05).$ In the first experiment the highest ROC rates (mg O$\sb2 \cdot$ kg$\sp{-1} \cdot$ h$\sp{-1})$ of yellowtail flounder, Pleuronectes ferruginea, and winter flounder, Pleuronectes americanus, followed a parabolic response over the temperature range tested (2-14$\sp\circ$C). Peak metabolism was at approximately 11$\sp\circ$C. The ROC rates of American plaice, Hippoglossoides platessoides, did not follow a parabolic response. In the second experiment winter flounder weighing 75-455 g had decreased ROC (mg O$\sb2 \cdot$ kg$\sp{-1} \cdot$ h$\sp{-1})$ as body size increased. The decrease in oxygen consumption tested over three temperatures was best described with a linear equation where MO$\sb2$ = 118.9 + 1.05(T) $-$ 0.16(W) + 14.3(R) $-$ 22.1(C). W was mean fish size (g), T was temperature ($\sp\circ$C), R was trial and C was tank. In the third experiment the ROC rates of winter flounder were determined at three stocking densities (5 kg $\cdot$ m$\sp{-3}$, 25 kg $\cdot$ m$\sp{-3}$, 50 kg $\cdot$ m$\sp{-3})$ and at 2.2 and 9.7$\sp\circ$C. Oxygen consumption and stocking density were inversely related. At 2.2$\sp\circ$C, the highest ROC rate was observed in the 5 kg $\cdot$ m$\sp{-3}$ group and lowest in the 50 kg $\cdot$ m$\sp{-3}$ group. At 9.7$\sp\circ$C the highest oxygen consumption rate was observed in the 25 kg $\cdot$ m$\sp{-3}$ group and the lowest in the 50 kg $\cdot$ m$\sp{-3}$ group. These data provide the minimum aerobic requirements of flounder during the on-growing phase of production. (Abstract shortened by UMI.).