AMLR_krill-densities_2001-2011

Acoustic densities of Antarctic krill in Scotia Sea from 01162001 to 03032011. Data were collected from research vessels using either Simrad EK500 (years 2001-2004) or Simrad EK60 (2005-2011) echosounders operating at 3 different frequencies (38, 120, and 200 kHz). Raw acoustic data were collected from calibrated echosounders and archived on the vessel and later on shore-based servers. The datasets were ultimately returned to the SWFSC for QA/QC, archiving and review. Krill were identified from these acoustic data using the distorted-wave Born approximation. (Reiss et al., 2008; Fielding et al., 2011). Data were exported using Echoview into gridded bins 5 m deep by 100 m horizontal over a total depth range of 5 m to a maximum of 505 m below the hulls of survey vessels.