Characterization of Frequency and Aggregation of the Antarctic Krill (Euphausia superba) Using Acoustics
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In this study, the dB difference and characteristics of krill swarms inhabiting Subarea 48.1, which includes the west and south of the South Shetland Island and the Elephant Island peripheries, were estimated to distinguish Antarctic krill, using acoustics. From April 13 to 24, 2016, acoustic data were collected along 24 survey lines using the frequencies 38 and 120 kHz, and middle trawling was performed at 7 stations. Using the difference between the dB values of two volume backscattering strength (Sv) frequencies (38 and 120 kHz), a clear acoustic distinction could be made between Antarctic krill (4.9 to 12.0 dB) and fish (−4.0 to −0.2 dB). The distributions and mean Sv of krill swarms in the Elephant Island peripheries and south of South Shetland Island were higher than those in the west of South Shetland Island. The mean length/ height ratio of krill swarms in the west of the South Shetland Island (64.5) was higher than that in the south (35.9) and the Elephant Island peripheries (33.8), with the length of the aggregations exceeding their height. Most krill swarms were distributed between the surface layer (less than 10 m below sea level) and within 200 m of water depth. These results are expected to serve as baseline data for evaluating krill density and biomass by distinguishing them from fish, using acoustics.
KeywordsAntarctic krill dB difference swarm characteristics South Shetland Island acoustics
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- Everson I (2000) Distribution and standing stock: the Southern Ocean. In: Everson I (ed) Krill biology, ecology and fisheries. Oxford, Blackwell Science, pp 63–79Google Scholar
- Fielding S, Cossio A, Cox M, Reiss C, Skaret G, Demer D, Watkins J, Zhao X (2016) A condensed history and document of the method used by CCAMLR to estimate krill biomass (B0) in 2010. CCAMLR, WG-EMM16/38Google Scholar
- Fielding S, Watkins J, Cossio A, Reiss C, Watters G, Calise L, Skaret G, Takao Y, Zhao X, Agnew D, Ramm D, Reid K (2011) The ASAM 2010 assessment of krill biomass for area 48 from the Scotia Sea. CCAMLR 2000 synoptic survey. CCAMLR, WG-EMM 11:20Google Scholar
- Foote KG (1987) Calibration of acoustic instruments for fish density estimation: a practical guide. International Council for the Exploration of the Sea, 144 pGoogle Scholar
- Kang DH, Hwang DJ, Kim SA (1999) Biomass and distribution of Antartic Krill, Euphausia superba, in the Northern part of the South Shetland Island, Antartic Ocean. J Korean Fish Soc 32:737–747Google Scholar
- Kang MH, Yoon GD, Choi YM, Kim JK (1996) Hydroacoustic investigations on the distribution characteristics of the anchovy at the south Region of East Sea. J Kor Soc Fish Tech 32:16–23Google Scholar
- Lawson GL, Wiebe PH, Stanton TK, Ashjian CJ (2008) Euphausiid distribution along the western Antarctic Peninsula. A. Development of robust multi-frequency acoustic techniques to identify euphausiid aggregations and quantify euphausiid size, abundance, and biomass. Deep Sea Res Pt II 55:412–431CrossRefGoogle Scholar
- Wang X, Zhao X, Zhang J (2015) A noise removal algorithm for acoustic data with strong interference based on post-processing techniques. CCAMLR, SG-ASAM 15/02:11Google Scholar