基于青海湖裸鲤耳石微结构的群体鉴别与增殖放流效果评估OA

Stock enhancement of Gymnocypris przewalskii constitutes a core conservation strategy for the recovery of this endemic and endangered species in the Qinghai Lake basin,and a scientifically rigorous quantification of its contribution to wild population restoration is a critical prerequisite for evidence-based management.In this study,we developed a validated identification framework for hatchery-released individuals by systematically comparing otolith microstructural signatures between wild and stocked populations,and further applied this approach to field-collected river samples to quantitatively evaluate the contribution of stock enhancement to G.przewalskii resource restoration.Significant inter-group differences were detected in the diameter of the first otolith growth ring:individuals from hatchery origin exhibited markedly larger first growth rings than their wild counterparts,a pattern primarily driven by the accelerated somatic growth during the first year of life under optimal artificial rearing conditions(i.e.,constant water temperature and ad libitum food availability),which led to faster otolith mineral deposition.Using the first growth ring diameter as a diagnostic phenotypic marker,we performed K-means clustering analysis on all river-captured samples,and the results showed that 17.09%(n=54)of the total sampled individuals were assigned to Cluster 1,which was dominated by hatchery-released fish and could be unambiguously classified as artificial-origin individuals.The age composition of the sampled river population ranged from 5 to 9 years,indicating that these hatchery-derived individuals originated from the stock enhancement activities implemented during 2015-2019 and have now recruited into the spawning population.Combined with the long-term dataset of annual hatchery release scale and wild resource dynamics of G.przewalskii in Qinghai Lake since 2002,we estimated that the overall contribution rate of artificial stock enhancement to the current resource restoration is approximately 21.42%.This study demonstrates that otolith microstructural analysis provides a robust,cost-effective technical support for quantifying the efficacy of stock enhancement programs,and confirms that targeted artificial release is a practical and effective measure to compensate for the recruitment deficit of natural G.przewalskii populations.