Ontogenetic change in the relationship between metabolic rate and body mass in a sea bream Pagrus major (Temminck & Schlegel)

Ontogenetic changes in the relationship between resting rate of oxygen consumption and wet body mass were examined at 20° C with the sea bream Pagrus major ranging from 0.00020 g (weight just after hatching) to 270 g (weight at 530 days old). There was a triphasic relationship between oxygen consumption of an individual fish M (μl min⁻¹) and body mass W(g). During a very early stage (weight 0.00020–0.00025 g), corresponding to the pre‐larval stage and with the transitional period to the post‐larval stage, there was no substantial change in body mass. The mass–specific metabolic rate M/W (μl g⁻¹ min ¹) showed no clear relationship to body mass as expressed by the equation M/ W=4.86 + 1.47 D, where D is age in days. During the post‐larval stage (weight 0.00031–0.005 g), M/W remained almost constant independent of body mass following the expression M= 12.5 W0.949. During the juvenile and later stages (weight 0.005–270 g), M/ W decreased with increasing body mass following the expression M= 6.3 W^0.821 which is significantly different from the expression for the post‐larval stage (P < 0.001). Ontogenetic changes in the metabolism‐body mass relationship are discussed from the viewpoint of relative growth of organs with different metabolic activities.