2009/2010—2011/2012年度夏秋季南奥克尼群岛水域南极磷虾捕捞群体年龄结构时空变化

利用南极磷虾渔业科学观察员收集的南极磷虾生物学数据,在将研究区域划分成60'×30'精细尺度单元的基础上,分析了南奥克尼群岛南极磷虾种群捕捞群体年龄结构的时空变化。结果表明,2009/2010年度,南极磷虾体长范围为33.2—69.0 mm,平均体长为51.8 mm,优势体长组为52—60 mm(52.3%),另在44—48 mm有一个次峰区;2010/2011年度,体长范围为22.9—59.3 mm,平均体长为44.5 mm,优势体长组为42—50 mm(56.8%);2011/2012年度,体长范围为18.5—59.4 mm,平均体长为41.7 mm,优势体长组为36—46 mm(67.3%)。三个年度间南极磷虾体长频次分布呈显著性差异(p0.001),且不具相似性(PSI=41.25—73.42)。2009/2010—2011/2012年度各旬别磷虾体长组可分成3个组,其中2011年2月上旬和2012年3月中旬可划分为一组,2010年1月下旬至2月中旬以及2011年2月中旬可归为一组,这几个体长组均呈双峰分布,其他的体长组划归为一组。1+和2+龄虾大多出现在离南奥克尼群岛最近的水域,而离南奥克尼群岛较远的单元中则多为4+龄以上的磷虾个体。

SPATIAL-TEMPORAL VARIATION IN POPULATION AGE STRUCTURE OF FISHERY-TARGETED ANTARCTIC KRILL(EUPHAUSIA SUPERBA) AROUND THE SOUTH ORKNEY ISLANDS IN AUSTRAL SUMMER-FALL DURING 2009/2010 AND 2011/2012

We used biological data on Antarctic krill (Euphausia superba Dana), collected by fishery observers of the Antarctic krill fishery, to investigate the spatial-temporal variation in age structure. The study area was divided into small-scale units with a spatial resolution of 30 minutes (latitude) by 1 degree (longitude). The results showed that in 2009-10 the standard length (SL) of Antarctic krill ranged from 33.2 to 69.0 mm, and the mean SL and dominant SL range were 51.8 mm and 52–60 mm (52.3%), respectively. A sub-modal range of 44-48 mm was also identified. In 2010-11, the SL ranged from 22.9 to 59.3 mm, and the mean SL and dominant SL range were 44.5 mm and 42-50 mm (56.8%), respectively, and in 2011-12, the SL ranged from 18.5 to 59.4 mm, and the mean SL and dominant SL range were 41.7 mm and 36-46 mm (67.3%), respectively. Among the three years, there was a significant variation in SL (p < 0.001) and no similarity in length frequency distribution (PSI = 41.25–73.42). Clustering analysis showed that SL classes could be divided into three groups among 10 days in a month during 2009-10 to 2011-12. The SL classes could be classified into groups based on the first 10 days in February 2011 and the middle 10 days in March 2012, on the last 10 days in January to the middle 10 days in February 2010 and the middle 10 days in February 2011. The other SL classes could be classified into another group. Age 1+ and 2+ Antarctic krill occurred in waters close to the South Orkney Islands, while age 4+ Antarctic krill were found in waters further from the Islands.