GEOGRAPHICAL DISTRIBUTION OF KRILL IN AMUNDSEN SEA, ANTARCTIC OCEAN, 2011 AND 2012

Abstract

The objective of the hydroacoustic survey is to know geographical (spatial/vertical) distribution of krill around Amundsen Sea, in January 2011 and February 2012. Hydroacoustic data were collected using a multi-frequency echo sounder (EK60, Simrad), configured with down-looking 38, 120 and 200 kHz split-beam transducers mounted in the hull of RVIB Araon. Acoustic surveys were divided into four transects in the Amundsen Sea: (1) near ice shelf, (2) center of coastal polynya, (3) pack ice zone near the polynya, (4) open sea. Simultaneously, net samplings were done to compare the acoustic data and zooplankton data. High concentrations of krill are mainly found at center of coastal polynya and pack ice zone near the polynya. The krill patches in the two zone formed thick layer and its depth was between surface and 200 m. Contrary to polynya, there wasn’t any krill patch in the open sea. Abundance and distribution of krill was highly variable near ice shelf. From net survey, Euphausia crystallorophias is dominant krill species in Amundsen Sea, while Euphausia superba is distributed in some area. From the studies, it shows that spatial distributions of krill in Amundsen Sea apparently differ with geographic area.K60, Simrad), configured with down-looking 38, 120 and 200 kHz split-beam transducers mounted in the hull of RVIB Araon. Acoustic surveys were divided into four transects in the Amundsen Sea: (1) near ice shelf, (2) center of coastal polynya, (3) pack ice zone near the polynya, (4) open sea. Simultaneously, net samplings were done to compare the acoustic data and zooplankton data. High concentrations of krill are mainly found at center of coastal polynya and pack ice zone near the polynya. The krill patches in the two zone formed thick layer and its depth was between surface and 200 m. Contrary to polynya, there wasn’t any krill patch in the open sea. Abundance and distribution of krill was highly variable near ice shelf. From net survey, Euphausia crystallo