自然产卵间断以来中华鲟幼鱼抵达与离开长江口时间及其生长的年际变化观察

中华鲟是国家一级重点保护野生动物,近年来野生中华鲟自然产卵行为异常中断给中华鲟种群保护和恢复带来巨大挑战。为了探究该异常现象对中华鲟生活史特征产生的可能影响,本研究根据2004-2020年长江口中华鲟幼鱼资源调查数据,分析中华鲟自然产卵行为异常前后长江口中华鲟幼鱼的种群特征及洄游习性变化。结果表明：(1)2014、2016、2018-2020年长江口水域未监测到中华鲟幼鱼,自中华鲟自然产卵行为异常后,长江口中华鲟幼鱼补充量出现中断的情况；(2)中华鲟幼鱼洄游习性发生显著变化,呈现首现时间提前(提前至4月中旬),终现时间延迟(延迟至10月下旬),出现时间延长(延长118天)的趋势；(3)中华鲟幼鱼生物学指标低于历史同期,最小体长和最小体重分别为7.0 cm和4.9 g。研究结果将为中华鲟繁殖行为、资源变动、产卵场变迁与修复重建等研究工作,以及中华鲟抢救性保护政策措施的制定提供重要的科学参考。

Interannual variation in migration habits and growth of juvenile Chinese sturgeon following interrupted natural spawning behavior in the Yangtze River Estuary

Chinese sturgeon Acipenser sinensis is an anadromous migratory fish species, which inhabits the Chinese coastal continental shelf areas and breeds in the Yangtze River Basin. The Yangtze River Estuary is an important migration passage of Chinese sturgeon. The Chinese sturgeon population is endangered, which has been listed as a top-level protected animal in List of key protected wild animals in China and a critically endangered species in IUCN Red List of Threatened Species. Since 2013, the abnormal interruption of natural spawning behavior of wild Chinese sturgeon has brought great challenges to the protection and restoration of Chinese sturgeon population. Based on the survey data of juvenile Chinese sturgeon resources in the Yangtze River estuary from 2004 to 2020, this study analyzed the population characteristics and migration habits of juvenile Chinese sturgeon in the Yangtze River estuary following the abnormal natural spawning behavior. The results show that:(1) Since natural spawning behavioral interruption of Chinese sturgeon, juvenile Chinese sturgeon was not detected in the Yangtze River estuary in 2014, 2016,2018, 2019 and 2020. The recruitment of juvenile Chinese sturgeon population in the Yangtze River estuary showed an interannual continuous fracture. (2) The migration habits of juvenile Chinese sturgeon changed significantly, it showed that the first occurrence time was advanced to mid-April, and the final occurrence time was delayed to late October, and the occurrence time span was extended by 118 days. (3) The biological indexes of juvenile Chinese sturgeon were lower than the same period in history; Their minimum body length and minimum body weight were 7.0 cm and 4.9 g respectively. To sum up, the juvenile Chinese sturgeon recruitment decreased year by year. The migration habit shows that the earlier the first occurrence time, the later the final occurrence time in the Yangtze River estuary.The results of this study will provide an important scientific reference for the protection of rare and endangered species of Chinese sturgeon.