Ontogenetic development and otolith microstructure in the larval and juvenile stages of mandarin fish Siniperca chuatsi

Abstract

The mandarin fish Siniperca chuatsi (Perciformes: Percichthyidae) is a commercially important freshwater fish in China. However, S. chuatsi populations have declined dramatically in most of the lake and river systems. In this study, ontogenetic development and sagittal otolith microstructure were studied for this species, and relationships between otolith microstructure patterns and life history events were established during early life history stages. Otolith growth increments were validated as being formed daily, and the first increment was formed three days after hatching (DAH), which coincided with the time of the first feeding. The relationship between body length and otolith radius was fitted by a piecewise linear regression with an inflexion point during the flexion stage at 9.0 mm body length $$(B_{\text{Lt}} = 1 4 8. 4 9 e^{{ - e^{ - 0. 0 4 (t - 3 6. 7 5)} }}$$ , r2 = 0.97, P < 0.05, n = 460). Accessory primordium formation corresponded to metamorphosis when the fish transitioned from the post-flexion larval stage to the juvenile stage. Thus, further research can use otoliths to re-construct the early growth and development of wild S. chuatsi populations. During early life history stages, allometric growth patterns showed that the eyes, mouth and head developed with priority, suggesting the essential organs related to feeding develop first. Further research should consider the biological significance of such morpho-functional developmental patterns during the early life history stages of this species.