This record describes scientific split-beam echosounder data collected on the 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 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 during the transit to/from the survey area, and a range of 700m while within the survey area in Antarctic waters. All frequencies were logged continuously for the extent of the voyage. A cold water calibration was performed at the Antarctic survey site, with the new calibration values applied to the dataset between 25 January and 27 February. Transit data were logging using calibration values from Hobart in June 8, 2018. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 11,511 files totalling 214 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_E03, Equipment Commissioning Sea Trials, which departed Brisbane on the 20th August 2017 and returned to Brisbane on the 24th of August 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 1500 m off the coast of Brisbane. All frequencies were logged continuously for the extent of the voyage. Sea trials were conducted specifically for the EK60 during this voyage to detect improvements in electrical noise after rewiring during the preceding port period. Specific data was collected at each of the drop keel positions to get baseline readings in both passive and active modes. During this time, the ship was stationary and all other acoustic instruments were turned off. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 143 files totaling 12.6 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 IN2025_V04, titled "Untangling the causes of change over 25 years in the southeast marine ecosystem - Voyage IV." The voyage took place between May 27, 2025 and June 28, 2025 (AEST), departing from Hobart and returning to Hobart. The Simrad EK80 split beam echosounders for 18, 38, 70 120, and 200 kHz were used to acquire acoustic backscatter data to a range of up to1500 m, between Hobart and Eden. Logging range was changed throughout the voyage based on depth. The 18, 38, 70 120, and 200 kHz frequencies were logged continuously for the extent of the voyage. The 333 kHz was set to passive for the duration of the voyage due to a known issue with the transducer. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 1,164 files totalling 112 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 IN2015_C02, Great Australian Bight Research Program: GAB deep-water pelagic and benthic ecosystem study which departed Port Lincoln on the 30 November 2015 and returned to Fremantle on the 22 December 2015. The Simrad EK60 split beam echosounders 12, 18, 38, 70 120, 200 and 333 kHz frequencies were used to acquire acoustic backscatter data to a range of 1500 m, around the Great Australian Bight. All frequencies except for the 12 kHz were logged continuously for the extent of the voyage. The 12 kHz was logged for a portion of the voyage, but was also set to passive mode periodically. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 998 files totaling 83.7 GB of raw data in this dataset. Some processing has been conducted on this data, which will be available through IMOS. 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_E01, Triaxus Sea Acceptance Testing & Calibrations Voyage, which departed Hobart on the 9th June 2018 and returned to Hobart on the 11th June 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 50 m, at the calibration site at White Rock in Storm Bay. Sphere calibrations were performed during this voyage using a 60 mm copper sphere (18, 38, 70 kHz) and 38.1 mm Tungsten Carbide sphere (120, 200, 33kHz). All frequencies were logged for the extent of the calibrations of the voyage. Data are stored in .raw, .bot and .idx format at CSIRO. There are 21 .raw files totalling 422 MB of raw data in this dataset. On-axis calibration processing using EchoView 8 has been conducted on this data. Additional information regarding this dataset is contained in the GSM in2018_e01 EK60 Calibration 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 IN2018_V07, SOTS: Southern Ocean Time Series Automated Moorings for Climate and Carbon Cycle Studies Southwest Tasmania which departed Hobart on the 20/08/2018 and returned to Hobart on the 25/08/2018. 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 the mooring deployment site and return. All frequencies were logged continuously for the extent of the voyage. The all frequencyies were set to passive for the whole of the voyage. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 591 files totalling 19.2 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 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 RV Investigator voyage IN2017_E02, Gear Trials which departed Hobart on the 31-March-2017 and returned to Hobart on the 2-April-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 1500 m, around the Huon marine reserve, south east Tasmania. All frequencies were logged [continuously/sporadically] for the extent of the voyage. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 47 files totalling 4.5 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_T01, titled: "Physical and biogeochemical gradients in the East Australian Current." The voyage took place from Hobart (TAS) to Brisbane (QLD) between April 5 and April 14, 2018. The Simrad EK60 split beam echosounders 18, 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data, between Brisbane and Hobart. All frequencies were logged sporadically for the extent of the voyage. The frequencies were set to passive for the periods of the voyage. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 2,175 files totalling 41.7 GB of raw data in this dataset. No processing has been conducted on this data. Data spans 5/04/2018 20:00 until 06/04/2018 06:00 UTC. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.