Krill distribution and environment in Subareas 48.1 and 48.2 from results of the RV Atlántida cruise in 2020

The Russian  krill research in Subarea 48.1 and 48.2 under CM 24-01 paragraph 2 were carried out by  RV “Atlantida”  in the period January-March 2020  including acoustic surveys, accompanied by a wide range of ecosystem studies on the biology of  krill and its habitat (hydrometeorological, oceanological and hydrochemical data) and  bio-productivity indices  (chlorophyll, primary production, phyto-, zoo- and ichthyoplankton).  This krill research was carried out in accordance with the CCAMLR Survey 2000 formats and CCAMLR recommendations.  The study area in Subarea 48.1 and 48.2 was about 480 thousand km².  Survey provides up-to-date information on krill biomass distribution and environments at varies spatial scales.  The total krill biomass estimated at the survey area was 39, 29 mln.t , CV=9,29%.  Statistical characteristics of krill biomass by stratum are shown. An analysis of oceanological conditions in January-March 2020 confirmed the main patterns of krill  distribution depending on the structure and dynamics of waters. Krill concentrations were observed in the zone of interaction between the waters of high latitude modification (Weddell Sea waters) and the waters of the southern periphery of the ACC  as well as in the marginal (shadow) zones, with eddies and gyres characteristic of shelf and slope areas. The krill length compositions are characterized by spatial heterogeneity, which is demonstrated by its distribution across strata and in different modifications of water masses (ACC  and the Weddell Circulation ).   The latter primarily relates to the content of the recruitment share. In the long term, the distribution patterns of krill and their habitat environment in Subarea 48.1 and 48.2 practically did not undergo significant changes