2015年5月黄海及东海北部大型水母分布及生物量估算

2015年5月搭载“北斗”渔业调查船、使用渔拖网的采样方式，在整个黄海及东海北部进行系统的走航式大面调查，记录了30°N—39°N海区内的大型水母种类组成、伞径大小及生物量分布，估算和比较了大型水母与其他渔业生物的生物量。结果表明，5月整个调查区，大型水母的总生物量估算值5.9万t，绝大部分由黄海中部的多管水母和洋须水母生物量贡献所致。出现的大型水母种类伞径分布呈单峰型。不同种类的水母分布具有明显地理区域和水文偏好性。其中，洋须水母主要分布于黄海中、北部50m水深以深水域，多管水母主要分布于黄海中部50m水深以浅的西侧以及整个东海北部；沙海蜇多为幼体，分布于黄、东海交汇区31°N—33°N间；霞水母较为集中出现于31°N以南、123°N以西近海。各水母种类的高密区的底层水温按洋须水母、沙海蜇、四叶小舌水母、霞水母呈升高趋势。东海多管水母分布区的底层水温与沙海蜇相近；黄海多管水母分布区的底层水温较洋须水母略高。沙海蜇和四叶小舌水母较其他水母的适温范围宽。霞水母和洋须水母处于相对高盐区域。

SPATIAL DISTRIBUTION AND BIOMASS OF LARGE JELLYFISH IN THE YELLOW SEA AND NORTHERN PART OF THE EAST CHINA SEA IN MAY 2015

To explore the species compositions and distributions of large jellyfishes at the beginning of the traditional jellyfish blooming season in the Yellow Sea and the East China Sea, a comprehensive fishery survey was designed and conducted aboard the R/V Beidou in May 2015. Jellyfish were sampled using a bottom trawl in codend net mesh size 24mm in 120 stations ranging 30°N-39°N in the Yellow Sea and the northern part of the East China Sea. The dominant large jellyfish species, their bell size, and biomass were recorded. Jellyfish included Ulmaridae, Aequorea spp., and Cyanea spp., Nemopilema nomurai, Liriope tetraphylla, and a species of Ulmaridae. The bell size frequency of these species followed normal distributions with a single peak. In addition, the total biomass of large jellyfish was estimated for about 59000 t, mostly Ulmaridae and Aequorea spp. in the central part of the Yellow Sea. Ulmaridae and Aequorea spp. were the most common and abundant species in the Yellow Sea, but the former was limited mainly in 50 m and deeper waters, while the latter preferred to the shallower water in the depth less than 50m. In addition, Aequorea spp. also occurred frequently throughout the northern part of the East China Sea. N. nomurai, Cyanea spp. and L. tetraphylla were common in the northern part of the East China Sea. Most individuals of N. nomurai were juvenile medusa, and they occurred in a narrow transition area (31°N-33°N) between the Yellow Sea and East China Sea. Cyanea spp. concentrated from inshore to the south of 31°N in the East China Sea. L. tetraphylla abounded in a few inshore stations of the northern part of East China Sea. N. nomurai and L. tetraphylla were eurythmic in a wider temperature range. Aequorea spp. in the Yellow Sea preferred slightly warmer waters than Ulmaridae, but they presented higher temperature adaptability similar to N. nomurai in the northern part of East China Sea. The bottom water temperature where species occurred frequently increased were in turn: Ulmaridae, N. nomurai, L. tetraphylla, and Cyanea spp. Comparatively, Cyanea spp. and Ulmaridae were adapted to higher salinity than other species.