The original calculation of B₀ arising from the CCAMLR-2000 survey was undertaken at the B₀ workshop held in La Jolla, USA, in May 2000 (SC-CAMLR-XIX, Annex 4, Appendix G).

A number of changes in assessing krill target strength (TS) and identifying acoustic targets have been introduced via both CCAMLR WG-EMM papers (e.g. Demer et al. 2007) and published literature (Demer and Conti, 2003; Conti and Demer, 2005) that led to the re-analysis of the CCAMLR-2000 survey at a workshop held in Cambridge, UK, in June 2010 (SC-CAMLR-XXIX, Annex 5).

There remains some ambiguity to the interpretation of what is the protocol used to derive the current estimate of B₀, and no single document is currently available to describe the full method. Prior to the 2016 CCAMLR SG-ASAM meeting we have amalgamated the existing documentation of the protocol (from previous CCAMLR meetings) and matlab/R analysis code that we will present at the ASAM meeting for endorsement. We envisage that this effort will then be summarised in a paper submitted to WG-EMM 2016 so that a single published document will exist with the most up-to-date method.

Raw and calibrated NASC from repeat acoustic transects sampled by commercial fishing vessels is one approach to collecting data to inform within season feedback management schemes. However, a lack of sufficient data exists from which to examine its efficacy. In addition to the time/monetary commitment by fishing nations to collect such data, a time series of data, like that collected by the U.S. AMLR Program in Sub-area 48.1, can provide background information to help develop these feedback approaches. In this paper I present some basic information from data collected by the U.S. AMLR Program along repeat transects sampled twice during summer between 1996 and 2011.  These data will be available during the SG-ASAM Meeting for investigation of potential utility in formulating plans for development feedback management strategies.

In 2010, CCAMLR tasked the Subgroup on Acoustic Survey and Analysis Methods (SG-ASAM) to recalculate the catch limit for Antarctic krill in the Scotia Sea based on updated acoustic algorithms developed since the first calculation in 2000. Subsequent to the 2010 SG-ASAM, code used to obtain biomass (B₀; tonnes) estimates was compiled and provided to the Secretariat for reference and use by others to derive biomass estimates. Over the last several years, attempts by many nations to use this collection of code has revealed inconsistencies and omissions in the documentation, complicating attempts by interested parties in using this approach to estimate biomass in other areas. Here we present new, more efficient, thoroughly documented, and generically applicable code for calculating acoustic biomass estimates for any area based on the CCAMLR 2000 survey methods. Using data from the South Orkney Island stratum during the CCAMLR 2000 survey, results from the new code are compared to the original and shown to be comparable. In 2010, CCAMLR tasked the Subgroup on Acoustic Survey and Analysis Methods (SG-ASAM) to recalculate the catch limit for Antarctic krill in the Scotia Sea based on updated acoustic algorithms developed since the first calculation in 2000. Subsequent to the 2010 SG-ASAM, code used to obtain biomass (B₀; tonnes) estimates was compiled and provided to the Secretariat for reference and use by others to derive biomass estimates. Over the last several years, attempts by many nations to use this collection of code has revealed inconsistencies and omissions in the documentation, complicating attempts by interested parties in using this approach to estimate biomass in other areas. Here we present new, more efficient, thoroughly documented, and generically applicable code for calculating acoustic biomass estimates for any area based on the CCAMLR 2000 survey methods. Using data from the South Orkney Island stratum during the CCAMLR 2000 survey, results from the new code are compared to the original and shown to be comparable. 

This paper is intended to provide a generalised example of a procedure for krill density estimation, based on a worked example from the Balleny Islands (WG-EMM-15/17).  Explicitly, this paper is not the CCAMLR krill density estimation procedure, but has been written as a discussion document for the 2016 SG-ASAM meeting.