Antarctic krill populations in the outflow region of the north-western Weddell Sea

A meso-scale zooplankton and krill net sampling survey was carried out in the north-western Weddell See and in Bransfield Strait/western Antarctic Peninsula during late January to early March 2013. The aim of the survey was to study the zooplankton composition and krill abundance and distribution in the outflow region of the Weddell Sea. Due to severe pack-ice conditions, more than half of the survey area was covered by ice during the summer season. Antarctic krill densities were found to be highest in the western Peninsula region and lower in ice-covered Weddell Sea waters. Overall krill density was below the longterm average of the area. New one-year-old recruits were scarce, the stock was dominated by two and three year old krill. Spawning occurred late and numbers of gravid females and larvae were low. Ice krill E. crystallorophias was abundant on the shelf of the north-western Weddell Sea. Thysanoessa macrura and salps Salpa thompsoni were far less abundant than the longterm average and were confined to the more northern, ice-free areas.