基于耳石微化学的长江禁捕前后鄱阳湖都昌水域刀鲚群体动态变化研究

Study on resource dynamics of Coilia nasus from Duchang waters in Poyang Lake based on otolith microchemistry before and after implementation of Yangtze River fishing ban

为了解长江禁捕对鄱阳湖都昌南部水域刀鲚(Coilia nasus)资源的影响,利用电子探针微区分析(EPMA)分别对该水域禁捕前(2014年)和禁捕后(2019年)刀鲚的洄游生态学特征开展了研究。结果显示,所有刀鲚个体耳石自核心至边缘均依次具有锶钙比(Sr/Ca×1000)<3、3~7以及<3的生境履历特征,表现为典型的溯河洄游履历。禁捕后刀鲚数量(17尾)明显多于禁捕前(2尾),体长[(28.1±2.3)cm]也长于禁捕前[(21.3±4.7)cm],且长于禁捕前的已有报道。此外,刀鲚耳石边缘低值区呈现多样化特征[2014年(125.0±63.6)μm、80~170μm,2019年(173.5±73.6)μm、20~290μm],表现出多个上溯群体在该水域混栖的现象。结合该水域多数个体性腺尚未成熟,且都昌南部水域(大矶山至和合乡水域)是刀鲚群体自江湖通道出入鄱阳湖中部和南部湖区及通湖河流(如饶河、信江等)的必经之路,得出都昌水域主要行使刀鲚洄游通道的生态功能,亟须加强保护。

In order to understand the effect of fishing ban on Coilia nasus resources in the southern Duchang waters in the Poyang Lake,we conducted an electron probe microanalysis(EPMA)to study the migratory ecological characteristics of C.nasus in the waters before(2014)and after(2019)fishing ban.The results show that the otolith of all individuals had three significant fluctuation phases of Sr/Ca ratios of<3,3–7 and<3 from the core to the edge,indicating a typical anadromous migration his-tory.The number of samples(17 tails)after fishing ban was significantly higher than that before the ban(2 tails),and the body length of the former[(28.1±2.3)cm]was longer than that of the latter[(21.3±4.7)cm],which was also longer than that of the former reported before fishing ban.In addition,the length of low-value area on the otolith edge showed diverse characteristics[(125.0±63.6)μm,80–170μm in 2014,(173.5±73.6)μm,20–290μm in 2019],which suggests the phenomenon of mixed habi-tat of multiple upstream groups in the local waters.Considering that most of the individual gonads in the area were not mature,and that the southern Duchang waters(Dajishan to Hehe Township)are the only way for the population to enter and exit the central and southern waters of the Poyang Lake and the rivers connecting the lake(Such as Raohe River and Xinjiang River),it is strongly suggested that corresponding effective protection of this key habitat should be enhanced since the area mainly plays the ecological function of migration channel for C.nasus.