Validation of daily increment formation in otoliths for Gymnocypris selincuoensis in the Tibetan Plateau, China.

Chengzhi Ding,Juan Tao,Yifeng Chen,Dekui He

doi:10.1002/ece3.1572

Abstract

Daily increment validation in fish otolith is fundamental to studies on fish otolith microstructure, age determination and life history traits, and thus is critical for species conservation and fishery management. However, it has never been done for Schizothoracine fish, which is the dominant component of fish fauna in the Tibetan Plateau. This study validated the daily increment formation of Gymnocypris selincuoensis, as a representative of Schizothoracine fish, by monitoring the growth of hatchery-reared larvae group and wild-caught post-yolk-sac larvae group under controlled experiments. The results from monitoring the hatchery-reared larvae group showed that sagittae and lapilli were found in yolk-sac larvae, and formed 5–7 days before hatching, but asterisci were not found until 11 days post-hatching. The first increment in sagittae and lapilli was formed in the first day after hatching. The daily periodicity of increment formation was examined and confirmed in sagittae and lapilli of both larvae groups. However, sagittae were better for age determination than lapilli for larvae at earlier days. For larval G. selincuoensis older than 50 days, lapilli were the only otolith pair suitable for larvae daily age determination. This study validated the daily increment formation in Schizothoracine fish for the first time has primary implications to other fishes from this subfamily.

Highlights

Increment validation in fish otolith is fundamental to studies on fish otolith microstructure, age determination and life history traits, and is critical for species conservation and fishery management (Campana and Neilson 1985; Jia and Chen 2009)
Otolith radius increased linearly with total length (TL = 0.094RL + 8.78, r2 = 0.82, n = 70; TL = 0.089RS + 8.34, r2 = 0.86, n = 70); this demonstrated that somatic and otolith growth were isometric at this life stage
The increments on sagitta and lapillus of the yolk-sac larvae were distributed in concentric circles which were quantified (Fig. 2A–C), the width of increments on otoliths from reared larvae and wild larvae were showed on Figure 1

Summary

Introduction

Increment validation in fish otolith is fundamental to studies on fish otolith microstructure, age determination and life history traits, and is critical for species conservation and fishery management (Campana and Neilson 1985; Jia and Chen 2009). Increment has been applied in age determination for larvae in days and juveniles, and is critical to study the early life history of fish (Campana and Neilson 1985). The utility of daily growth increments in providing estimates of age have been validated in a wide variety of species, the increment deposition in otoliths is varied among different species

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Conclusion