This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2021_V01, "Quantifying krill abundance for krill monitoring and management off the Australian Antarctic Territory", which departed Hobart on the 29th January 2021 and returned to Hobart on the 24th March 2021 (AEST). The Simrad EK80 split beam echosounders 18, 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a maximum range of 1500 m between Hobart and near Mawson station, Antarctica. All frequencies were logged continuously for the extent of the voyage. Acquisition settings (pulse length, power) were varied for the transit and survey portions of the voyage according to science requirements. Specific settings for each time period can be obtained from the GSM voyage report. From 1 Feb, 2021 the 18kHz WBT was replaced with the 18kHz GPT which was run for the remainder of the voyage. A calibration was performed at the survey location on 13 Feb 2021. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 3192 files totalling 295 GB of raw data in this dataset. No processing has been conducted on this data. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2018_V01, Detecting Southern Ocean change from repeat hydrography, deep Argo and trace element biogeochemistry & CAPRICORN which departed Hobart on the 11 January 2018 and returned to Hobart on the 22 February 2018. The Simrad EK60 split beam echosounders 18, 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a range of 1500 m, between Hobart and 66°S. All frequencies were logged continuously for the extent of the voyage but no personnel were on board to monitor the acquisition. Data are stored in .raw, .bot and .idx format at CSIRO. There are 1041 .raw files totalling 94.8 GB of raw data in this dataset. Processing has been conducted on this data for the return transit from 66S to Hobart.

This record describes multibeam echosounder data collected on RV Investigator voyage IN2019_V01, The availability of Antarctic krill to large predators and their role in biogeochemical recycling in the Southern Ocean which departed Hobart on the 19th January, 2019 and returned to Hobart on the 5th of March, 2019. The Kongsberg EM122 multibeam echosounder was used to acquire seafloor bathymetry, backscatter information and watercolumn backscatter between Hobart and Antarctica. The EM122 provides a 1 degree by 1 degree angular resolution. The echosounder's nominal frequency is 12 kHz. Data are stored in .all raw format for bathymetry and backscatter and .wcd format for watercolumn backscatter at CSIRO. There are 965 files totalling 51.9 GB of raw bathymetry/backscatter data and 943 files totalling 106 GB of raw water column data in this dataset. Sound velocity profiles were applied to this data during data acquisition. Bathymetry data contained in *.all format are corrected for motion and position. Tide corrections were not applied to the processed data. Processed data had outliers removed. Processed line data are available in *.gsf and ascii format, and processed bathymetry in geotiff format. Additional information regarding this dataset, including information on processing streams, is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes multibeam echosounder data collected on RV Investigator voyage IN2019_V01, The availability of Antarctic krill to large predators and their role in biogeochemical recycling in the Southern Ocean which departed Hobart on the 19th January, 2019 and returned to Hobart on the 5th of March, 2019. The Kongsberg EM710 MKII multibeam echosounder was used to acquire seafloor bathymetry and backscatter information for a limited time during the transit off/on the shelf to/from Hobart. For the majority of the voyage, the EM710 MKII was not operated due to depth ranges beyond the operating capabilities or due to interference with the water column acoustic instruments of greater priority. The EM710 MKII provides a 0.5° by 1° transmit and receive angular resolution respectively. The echosounder's nominal frequency range is from 40 to 100 kHz. Data are stored in *.all raw format for bathymetry and backscatter at CSIRO. There are 35 files totalling 6.91 GB of raw data in this dataset. Sound velocity profiles were applied to this data during data acquisition. Bathymetry data contained in *.all format are corrected for motion and position. Tide corrections were not applied to the processed data. Processed data has had outliers removed. Processed line data are available in *.gsf and ascii format, and processed bathymetry in geotiff format. Additional information regarding this dataset, including further information on processing streams, is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2022_V08, titled "Biodiversity Assessment of Australia’s Indian Ocean Territories" which departed Darwin on September 30 and returned to Fremantle on November 3, 2022. This was a continuation of voyage IN2021_v04. The Simrad EK60 split beam echosounders for 18 kHz and Simrad EK80 split beam echosounders for 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a range of 250 m (shallow water) or 1500 m (deep water) between Darwin and Fremantle. All frequencies were logged continuously for the extent of the voyage, except on occasion around Cocos (Keeling) Island and Muirfield Seamount when the 70 and 120 kHz frequencies were set to passive to avoid interference with the EM710 when conducting shallow multibeam bathymetry surveys. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 2138 files totalling 149 GB of raw data in this dataset. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2017_V05, Long-term recovery of trawled marine communities 25 years after the world’s largest adaptive management experiment, which departed Broome on the 11 October 2017 and returned to Henderson on the 10 November 2017. The Simrad EK60 split beam echosounders, 18, 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a range of 100 m, around the Northwest Shelf. All frequencies were logged continuously for the extent of the voyage. Data are stored in .raw, .bot and .idx format at CSIRO. There are 1041 .raw files totalling 55.6 GB of raw data in this dataset. No processing has been conducted on this data. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2016_E01, 'East Tasman Plateau – key to unravelling the onset of the Antarctic Circumpolar Current/MNF Equipment Sea Trials,' which departed Hobart on the 17 August 2016 and returned to Hobart on the 22 August 2016. The Simrad EK60 split beam echosounders 18, 38, 70, 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a maximum range of 1500 m between Hobart and the Cascade Seamount. All frequencies were logged continuously for the extent of the voyage. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 109 files totalling 9.46GB of raw data in this dataset. No processing has been conducted on this data. A calibration was performed during this voyage on August 17. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2018_V06, which departed Hobart on the 22-Nov-2018 and returned to Hobart on the 19-Dec-2018. The Simrad EK60 split beam echosounders [12], 18, 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a range of [range] m, Huon, Tasman Fracture Marine Parks and the St Helens seamount, Tasmania.. All frequencies were logged continuously for the extent of the voyage The frequencies were] set to passive for the periods when tracking towed bodies using USBL. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 4690 files totalling 90 GB of raw data in this dataset. No processing has been conducted on this data. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2017_V02, 'SOTS: Southern Ocean Time Series automated moorings for climate and carbon cycle studies southwest of Tasmania' which departed Hobart on the 17 March 2017 and returned to Hobart on the 28 March 2017. The Simrad EK60 split beam echosounders 18, 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a range of 0-1500 m, around Southern Ocean. All frequencies were logged continuously for the extent of the voyage. The frequencies were set to passive for the periods during the voyage. Data are stored in .raw, .bot and *.idx format at CSIRO. There are [XXXX] files totalling [XXXX] GB of raw data in this dataset. No processing has been conducted on this data. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2017_V03, 'Sampling the abyss: latitudinal biodiversity patterns along the base of Australia’s eastern continental margin' which departed Bell Bay on the 15 May 2017 and returned to Brisbane on the 16 June 2017. The Simrad EK60 split beam echosounders 18, 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data when possible. All frequencies were logged mainly when transitting between sites as all ship acoustics were turned off when listening for beacon signals on most operations. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 45.5 GB of raw data in this dataset. Amy Nau, will be processing this data. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.