长江刀鲚国家级水产种质资源保护区(安庆段)刀鲚资源现状

长江刀鲚（Coilia nasus）国家级水产种质资源保护区安庆段（简称"保护区"）位于刀鲚洄游区间的上段,生态环境优良,为掌握其刀鲚资源现状,于2018年4-7月进行调查研究,结果显示,保护区刀鲚资源密度分别为（0.09±0.07）尾/（10⁴ m³）和（4.46±3.43） g/（10⁴ m³）;刀鲚体长优势组为250~300 mm,体重优势组为<50 g。整体上,保护区刀鲚资源现状不容乐观,刀鲚小型化趋势明显。刀鲚洄游的时间特征显示,长江安庆段刀鲚主要洄游期为4月初至7月,高峰期为5月中旬至6月下旬,洄游后期刀鲚规格有增大趋势。空间上,刀鲚资源密度表现为保护区核心区高于实验区。此外,刀鲚性别和性腺发育情况抽样结果显示,整体上刀鲚雌雄比为1.02：1,但时间上雌雄比变幅较大,早期雄性个体较多,后期雌性个体较多,雌雄性腺主要发育期均为III期,6月开始出现发育至V期的个体;此外本研究捕获到摄食刀鲚,其数量占比为6.38%。本研究积累了长江禁捕前保护区刀鲚资源的系统数据,旨为后期刀鲚资源恢复评估和保护区管理提供重要依据。

Status of Coilia nasus resources in the National Aquatic Germplasm Resources Conservation Area in the Anqing Section of the Yangtze River

The national aquatic germplasm resources conservation area of Coilia nasus in the Anqing Section of the Yangtze River ("conservation area" for short) is located at the upper section of the migration interval of C. nasus, with a favorable ecological environment. To understand the current status of C. nasus resources, an investigation was conducted from April to July 2018. The results showed that C. nasus resource densities in the conservation area were (0.09±0.07) ind/(10⁴m³) and (4.46±3.43) g/(10⁴m³), and the dominant body length and weight of C. nasus were 250-300 mm and <50 g, respectively. Generally, C. nasus resource status in the conservation area was not optimistic, and C. nasus miniaturization was observed during the investigation. The temporal characteristics of C. nasus showed that the migration period was from early April to July in the Anqing section of the Yangtze River, and the peak period was from mid May to late June. Furthermore, C. nasus abundance showed an increasing trend in the late migration period. Spatially, C. nasus density in the core conservation area was higher than that in the experimental area. In addition, the gender and development stages of sampling results show that the ratio of males to females was 1.02:1, but the range was larger; the males developed earlier, and females developed later. The main development stage of testes and ovaries were III, and gonad development for stage V began in June. In this study, C. nasus with gastric contents of 6.38% were found. This study documented systematic C. nasus data in the Yangtze River pre-fallow reserve, which will provide an important basis for the recovery assessment of this species and conservation management in the future.