Hydroacoustic Observation of Antarctic Krill (Euphausia superba) in Atlantic Sector of Antarctica During 2010/11 season

Abstract

Hydroacoustic observations of Antarctic krill were made during the 27th Antarctic expedition of the RV "Polarstern" in CCAMLR Subareas 48.1, 48.2, 48.5 and 48.6 including in the central part of the Weddell Sea. Hydroacoustic data were collected using two-frequency echo sounder (70 and 120 kHz) "SIMRAD EK 60". Nautical Area Scattering Coefficient (NASC) was used for characteristic of krill density. NASC was calculated from 10 to 300 m depths with EDSU 5 nm. Maximal NASC values (average 44,4+-3,1 m2/n.m2) were recorded in the Antarctic Peninsula region (Subarea 48.1). Increasing of NASC was recorded in regions corresponding to the Antarctic Circumpolar Current, the Coastal Current and the circulation around the Maud Rise. NASC values in the central part of the Weddell Sea (between 15 degrees and 45 degrees W) were extremely low, mainly less than 1 m2/n.m2. Extremely low NASC indicates the absence of krill swarms in the central part of the Weddell Sea and probably connected with large-scale circulation of the Atlantic sector of Antarctica.