鄱阳湖通江水道鱼类空间分布特征及资源量评估

Spatial distribution and biomass assessment of fish in the channel connecting the Lake Poyang and the Yangtze River

于2014年9月24至26日在鄱阳湖通江水道湖口至屏峰段使用SIMRAD EY60回声探测仪对鱼类资源进行水声学调查.结果显示,鄱阳湖通江水道鱼类目标强度平均值为-56.4±6.4 d B,范围为-69.9^-32.1 d B;估算的平均全长为7.6 cm,范围为1.2~98.0 cm;鱼类资源的平均密度为53.7 ind./1000 m3,范围为0~441.7 ind./1000 m3.在水平分布上,鱼类主要分布在湖口县、鞋山和屏峰附近3个水域.区域Ⅰ和区域Ⅲ的鱼类密度显著高于区域Ⅱ的鱼类密度;区域Ⅲ的鱼类个体大小显著小于区域Ⅰ和区域Ⅱ.在垂直分布上,多数鱼类栖息于主河槽的深水区,且大个体更倾向于深水区.在此基础上,利用Arc GIS地统计插值方法估算鄱阳湖通江水道湖口至屏峰山水域鱼类总数量约为6.2×107ind.,总生物量约620 t.结果表明,鄱阳湖通江水道是鱼类重要的栖息地,建议加强该水域的保护,保持鄱阳湖与长江的自然连通.

Channels between lakes and rivers play a crucial role in maintaining fish population dynamics and their diversity in floodplains. In order to better understand the spatial distribution and the biomass of fish in the chamiel coimecting the Lake Poyang and the Yangtze River, a mobile hydroacoustic survey was conducted in September 2014, using Simrad EY60 split-beam echo sounder （200 kHz） .The spatial distribution of fish density and biomass for each cell of the studied region was derived from the spa-tial interpolation with geostatistics of ArcGIS. The results showed that the mean target strength （ TS） in the investigated areas is -56.4±6.4 dB and the mean total length is about 7.6 cm, ranging from 1.2 to 98.0 cm. Average fish density in the channel was 53.7 ind./1000 m3 , ranging from 0-441.7 ind./1000 m3. Uorizontally, fish assemblages were unevenly distributed in the investi-gated areas and concentrated mainly in three areas, that is, the section near liukou Country, Xieshan and Pingfeng Hill, respec-tively. The most striking feature in fish density was the concave-shaped distribution in the channel along the water flow direction （from lake to river） .The fish size （ total length） in the area near Lake Poyang （Area m ） was significantly smaller than that in the waters near Yangtze River （Area 1） and the transition zones （Area n ）. One possible reason for this might be a large number of young- of- the-year fish emerged after spawning period. Fish density increased vertically from the upper layer of the water to the lower layers. Meanwhile, our results supported the generality of the phenomenon of increasing fish size with increasing depth （i. e., big-ger-deeper phenomenon）. In addition, the total amount of fish biomass in the investigated area was estimated to be 6.2x 107 ind., up to 620 tons. Our findings suggested the need to enhance the protection for these essential fish habitats. This study also contrib-utes to the knowledge of the current state of fish resources and can be useful for proper resources conservation and effective ecosystem management of the floodplain biodiversity.