Early Morphological Development and Allometric Growth Patterns in Hatchery-Reared Red Porgy (Pagrus pagrus)

Abstract

Morphological development and allometric growth were investigated in the red porgy, Pagrus pagrus, during larval development until the end of weaning at 46 days after hatching (DAH). Total length (TL) of newly hatched larvae was 2.77±0.09 mm (mean±SE). Onset of exogenous feeding occurred at 4 DAH (3.74±0.13 mm TL). Initial swimbladder inflation occured at 10 DAH (4.22±0.18 mm TL) and post-inflation became more elongate at 16 DAH (4.95±0.26 mm TL). Notochord flexion occurred between 22 DAH (5.56±0.43 mm TL) and 34 DAH (8.22±0.63 mm TL). At the end of the weaning at 46 DAH, TL of larvae was 15.81±1.36 mm. According to individual measurements of a total of 1026 larvae of 18 body parameters for allometric growth, in 19 of 35 respective regression equations, the allometry coefficients were positive, while coefficients of 7 equations showed negative allometry. The majority of all allometric changes from inflection point were expressed during the larval stage and were integrated with the metamorphosis stage. Inflections in body proportion changes occurred mainly at TL values of 3.74, 4.22 and 5.56 mm, coinciding with mouth opening, initial swimbladder inflation and flexion of notochord, respectively.