Ontogeny of respiratory area of a marine teleost, porgy, Pagrus major

Relationships of respiratory areas (gill, body surface and fin areas) (A) to body mass (W) were determined with a marine teleost, the porgy Pagrus major of 0.0002-1230 g (just after hatch to 3+ years old), based on the allometric formula A = αW^β. (1) Early larvae (0.0002-0.0003 g) did not have the secondary lamellae that were responsible for gas exchange at the gills. After this stage, a tetraphasic relationship was observed between lamellar area (total area of secondary lamellae, often called gill area) (GA_L) and body mass. During the late larval and early juvenile stages, the GA_L-W relationship showed a triphasic positive allometry with β-values of 3.773, 1.561 and 1.111 corresponding to the first half of the late larval stage (0.00034-0.001 g), the second half of the stage (0.001-0.01 g) and the early juvenile stage (0.01-0.1 g), respectively. During the squamated juvenile and later stages (0.1-1080g). there was a negative allometry with a β-value of 0.813. (2) A triphasic relationship was observed between the total cutaneous surface area (body surface area and fin area) (CA_b+f) and body mass. During the early larval stage, in which an increase of body mass was very small, from 0.0002 to 0.00025 g, CA_b+f/W increased with growth with a β-value of 3.986. After this stage, the CA_b+f-W relationship showed a diphasic negative allometry with β-values of 0.562 during the late larval stage (0.00028-0.0045 g) and 0.652 during the early juvenile and later stages (0.0045-1230g). (3) Based on these results, factors controlling the metabolism-size relationship are discussed.