南极半岛邻近海域南极大磷虾(Euphausia superba Dana)的数量组成和分布

The Abundance, Distribution, and Stage-Specific Compositions of Euphausia superba in the Water Around the Antarctic Peninsula

中文关键词: 南极大磷虾  数量分布  发育期  生长率  南极半岛

英文关键词: Euphausia superba  Spatial distribution  Stage-specific composition  Growth rate  Antarctic Peninsula

中文摘要:

      根据2010年1月23日2月13日在南极南设得兰群岛和南奥克尼群岛邻近海域渔场采集的南极大磷虾(Euphausia superba Dana)样品，分析了南极大磷虾数量、个体体长分布和发育期组成等种群结构特点。样品由330 μm和500 μm浮游生物网垂直拖网和表层水平拖网两种采集方式所获。结果显示，采集样中，南奥克尼群岛水域的南极大磷虾平均密度为1.92 ind/m3，高于南设得兰群岛水域的相应值(0.35 ind/m3)；出现的南极大磷虾个体发育期包括CI至CIII期原蚤状幼体、FI至FIV期和FVI期蚤状幼体、未成体、成体(包括雌体和雄体)；各发育期个体中，原蚤状幼体数量较多；原蚤状幼体、蚤状幼体、未成体及成体的体长范围(平均体长)分别为1.76–4.96 mm (3.48 mm)、3.95–14.80 mm (5.96 mm)、16.87–39.85 mm (36.10 mm)、40.00–58.96 mm (43.94 mm)。CIII期原蚤状幼体和FI期蚤状幼体的生长率较高。推测，南奥克尼群岛水域南极大磷虾生殖季节始于9月末，集中出现在12月中上旬；而南设得兰群岛生殖季节应早于上述水域。比较两种采集方式，南极大磷虾在水平网中的出现频率和个体出现数量均高于垂直网采集样的相应值，建议传统垂直拖网与水平拖网两种采样方式有效结合，可促进更全面了解大磷虾水平分布和种群结构特点。

英文摘要:

      To characterize the structure of Antarctic krill population and to evaluate the fishery resources, we analyzed the stage-specific abundance and distribution of Euphausia superba based on the data collected in the main krill fishing grounds nearby the South Shetland Islands (CCAMLAR subarea 48.1) and the South Orkney Islands (CCAMLAR subarea 48.2) from January 23 to February 13 in 2010. There were two sampling methods used in the survey. One was the vertical haul from 200 m depth to the surface layer using plankton net of which the mesh size was 330 μm. The other was the horizontal haul on surface layer and the mesh size was 500 μm. E. superba was found in 39% of the sampling stations in the surveyed area. The mean density in the water around the South Orkney Islands was 1.92 ind/m3, which was higher than the value of 0.35 ind/m3 in the water around the South Shetland Islands. The developmental stages of the sampled E. superba covered the calyptopsis stages (CI to CIII), the furcilia stages (FI to FIV and FVI), juvenile and adult. Nauplius and furcilia FV were not observed in our samples. Individuals at stages CI to CIII were the most abundant. The length ranges at stages of calyptopsis, furcilia, juvenile and adult were 1.764.96 mm (mean 5.15 mm), 3.9514.80 mm (5.96 mm), 16.8739.85 mm (36.10 mm) and 40.0058.96 mm (43.94 mm) respectively. High growth rates of larval E. superba appeared at stages CIII and FI. According to the portions of individuals from different developmental stages, we deduced that the spawning season of E. superba in the water around the South Orkney Islands started in late September and peaked in early December, which was later than that of krill individuals in the water around the South Shetland Islands. The abundance of E. superba was higher in samples collected with the surface net method than with the vertical haul method, and there was also a remarkable difference in the stage-specific compositions between the two sampling methods. Therefore our study suggested that the surface sampling method could be an effective supplement to the traditional methods in the study of the spatial distribution and the growth of the krill.