This document outlines the preliminary results of an Australian survey of CCAMLR Division 58.4.2 (the South West Indian Ocean Sector of the Southern Ocean 30-80°E) in January-March 2006, which was designed around an acoustic biomass survey for krill and a large-scale oceanographic survey. The survey is intended to produce a new estimate of krill biomass (B0) for this Division so that a revised precautionary catch limit can be established by CCAMLR. The survey utilised a standardised design as adopted in previous B0 surveys in the CCAMLR Area and was designed so that the results would be compatible with the 1996 BROKE (Baseline Research on Oceanography, Krill and the Environment) survey of the adjacent CCAMLR Division 58.4.1 which collected information on a wide range of ecological parameters. The survey was conducted from a single ship, the RSV Aurora Australis, and consisted of 11 meridional transects, between 30° and 80°E. On each transect a range of underway data were obtained and on six transects detailed sampling was conducted at predetermined stations. This background paper provides an overview of what was achieved by this survey; the detailed results are currently being analysed and are being prepared for a special Issue of Deep-Sea Research for publication in 2008.