Osteological ontogeny and allometric growth in larval and juvenile turbot (Scophthalmus maximus)

Abstract

Skeletal development is crucial for fish fry breeding because of its influence on external morphology and functional exercise. Skeletal deformity generally occurs during the breeding process of cultured fish and usually results in movement difficulty, growth retardation, and even extremely high mortality. Severe deformity in breeding can lead to significant financial losses and restricts sustainable development of the fish aquaculture industry. Turbot (Scophthalmus maximus) is an important mariculture fish species with high commercial value in China. In the present study, we systematically investigated the growth characteristics, timing and progression of skeletal development, types and incidence of skeletal deformities, and their relationships in turbot during the breeding process. The results of the study revealed that allometric growth in the cranium, spine, and caudal fins occurred during the early developmental period, and the skeleton associated with jaw elements, gill components, and the caudal fin appeared and ossified preferentially. The timing and progression of skeletal development was significantly correlated with the functional requirement for food ingestion, respiration, and swimming capacity. Moreover, 14.15% incidence of deformities during the larval and juvenile stages were observed, including albinism (6%), uncoordinated appearance (4.5%), spinal deformities (2.3%), cranium deformities (0.5%), and fin deformities (0.85%). Spinal and cranium deformities significantly affected external morphology and growth. Albinism was the major type of abnormality in the appearance of turbot, although albinism had no significant effect on growth and development. The results of the present study provide useful information for the early detection of skeletal deformities and for the optimization of fish fry breeding technologies.