Acoustic determination of the distribution of fish and krill across the Scotia Sea in spring 2006, summer 2008 and autumn 2009
Acoustic determination of the distribution of fish and krill across the Scotia Sea in spring 2006, summer 2008 and autumn 2009
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DOI：
10.1016/j.dsr2.2011.08.002
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发表时间：
2012-01-01
影响因子：
3
通讯作者：
Venables, Hugh J.
中科院分区：
文献类型：
--
作者：
Fielding, Sophie;Watkins, Jonathan L.;Venables, Hugh J.
对从南奥克尼群岛到南乔治亚岛西北部整个斯科舍海的八个测站的横断面进行了多频声学反向散射数据的检查。这些样线在澳大利亚春季（2006 年 11 月）、夏季（2007 年 12 月/2008 年 1 月）和秋季（2009 年 3 月）重复进行。 dB 识别窗口 (Sv120-38) 识别出主导声学反向散射的两种类型的散射体； Sv120-38 为正值表示南极磷虾（南极磷虾），Sv120-38 为负值则表示有鳔的中层鱼类，例如蚴鱼。在斯科舍海北部的各个季节，由于成群的蜈蚣鱼造成的声学反向散射都更大，并且随着平均海水温度和绝对动态高度的增加而显着增加。学校分析发现，在鱼类声学反向散射较高的站点上有更多的鱼群。从春季到秋季，鱼群数量增加，分布更南，发生深度更深。使用目标强度模型计算的磷虾密度在春季（27.7 g m(-2)）和夏季（27.2 g m(-2)）相似，但2009年秋季较低（2.2 g m(-2)）。对群体特征的分析表明，在春季巡航期间，磷虾平均密度较高是由于少数群体中含有大量小磷虾，特别是在调查区域的南部。相比之下，在夏季巡航中，磷虾平均密度较高，这是由于大量磷虾群中大型磷虾数量较少所致。最后，在秋季，磷虾密度较低，因为磷虾群数量较少，其中含有少量大型磷虾。磷虾群的平均深度春季为58 m，夏季为94 m，秋季为123 m，调查区北部磷虾群分布较远、较深、磷虾较少且较小。斯科舍海磷虾和成群中层鱼类的纬度和垂直分布发生了大规模变化。这种水平和垂直分布的季节性重组将改变这些猎物在生态系统中的作用。 (C) 2011 Elsevier Ltd. 保留所有权利。
Multifrequency acoustic backscatter data were examined from transects at eight stations across the Scotia Sea, from the South Orkneys to the north west of South Georgia. These transects were repeated in austral spring (November 2006), summer (December 2007/January 2008) and autumn (March 2009). A dB identification window (Sv120-38) identified two types of scatterers dominating the acoustic backscatter; a positive Sv120-38 indicative of Antarctic krill (Euphausia superba) and a negative Sv120-38 indicative of mesopelagic fish with swim bladders, such as myctophids. Acoustic backscatter attributed to schooling myctophid fish was greater at stations in the north of the Scotia Sea across all seasons and found to increase significantly with increasing mean sea temperature and absolute dynamic height. A schools analysis identified more fish schools at the stations with high fish acoustic backscatter. The number of fish schools increased, were distributed further south, and occurred deeper from spring through to autumn. Krill density, calculated using a target strength model, was similar in spring (27.7 g m(-2)) and summer (27.2 g m(-2)), but lower (2.2 g m(-2)) in autumn 2009. An analysis of swarm characteristics showed that during the spring cruise the high mean krill density resulted from a small number of swarms containing a large number of small krill, particularly in the south of the survey region. In contrast in the summer cruise the high mean krill density resulted from a large number of swarms containing a low number of large krill. Finally, in autumn the low krill density resulted from a small number of swarms containing a small number of large krill. Krill swarms were located at a mean depth of 58 m in spring, 94 m in summer and 123 m in autumn and were generally further apart, deeper, contained fewer krill and smaller in the north of the survey region. Large-scale shifts in the latitudinal and vertical distribution of krill and schooling mesopelagic fish in the Scotia Sea were observed. This seasonal reorganisation in both horizontal and vertical distribution will alter the role of these prey items in the ecosystem. (C) 2011 Elsevier Ltd. All rights reserved.