Morphological Development and Allometric Growth in Hatchery-Reared Caspian Shemaya (Alburnus chalcoides): from Hatching to The Juvenile Stage

摘要

Morphological development and allometric growth were investigated in hatchery-reared Capsian shemaya, Alburnus chalcoides, from hatching to the juvenile stage at a temperature of 25.13± 1.61℃. The newly hatched larvae were 4.69±0.27 mm in total length (LT). Mouth opened 3 days after hatching (DAH) and initial swimbladder inflation occurred at 5 DAH. Exogenous feeding started at 6 DAH and the yolk sac was completely exhausted one day later. Squamation was initiated at 46 DAH and completed until 57 DAH. Based on the external morphology, early development of A.chalcoides was divided into five periods: yolk-sac stage 0-6 DAH (4.69-7.61 mm LT), preflexion stage 7-9 DAH (7.73-7.88 mm LT), flexion stage 10-18 DAH (8.20-9.60 mm), postflexion stage 19-45 DAH (9.30-19.97 mm LT) and juvenile stage 46-57 DAH (21.66-27.25 mm LT). During the first 4 weeks after hatching, there was an evident priority to develop feeding, swimming and respiratory ability by promoting intense growth in head and tail parts. Following this period, there was a clear reduction in growth coefficients.The allometric growth changes in Capsian shemaya during early life reflect the selective organogenesis directed towards survival priorities.