This dataset comprises still images collected using a trawl headline camera during the RV Investigator voyage IN2023_V05, titled "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 1)." This was the first survey of the South East Australian Marine Ecosystem Survey (SEA-MES) Project. The voyage was conducted between 27 June 2023 and 29 July 2023 and sampled the south-eastern Australian continental shelf and upper slope from the Freycinet Peninsula to north of Eden. The trawl headline camera was deployed during fish trawling operations to capture imagery of near-seafloor environments and biological interactions in the trawl path. The still images provide visual records of benthic habitat characteristics, fish and invertebrate assemblages, and species behaviour immediately prior to capture. These data complement physical and biological sampling by providing contextual information on habitat type, species presence, and trawl performance. The dataset supports assessments of habitat–fauna relationships, validation of trawl catch data, and long-term monitoring of ecosystem change within the SEA-MES study region, contributing to the establishment of new biological and environmental baselines for south-eastern Australia.

This record describes multibeam echosounder data collected on RV Investigator voyage IN2023_V05, titled "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 1). The voyage took place between June 28, 2023 and July 30, 2023 (AEST), departing from Hobart and returning to Hobart. The Kongsberg EM710 MKII multibeam echosounder was used to acquire seafloor bathymetry and backscatter information [and watercolumn backscatter] between/around [XXXXArea of survey]. 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 and *.wcd format for watercolumn backscatter at CSIRO. There are 1,470 files totalling 198 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. GPS tide was computed using the EGM2008 model and applied to the processed data. Processed data has had outliers removed. Processed line data are available in *.gsf and ascii format, and processed bathymetry grids 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 multibeam echosounder data collected on RV Investigator voyage IN2023_V05, titled "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 1). The voyage took place between June 28, 2023 and July 30, 2023 (AEST), departing from Hobart and returning to Hobart. The Kongsberg EM122 multibeam echosounder was used to acquire seafloor bathymetry, backscatter information and watercolumn backscatter between Hobart and Sydney. 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 318 files totalling 30.1 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. GPS tide was computed using the EGM2008 model and applied to the processed data. Processed data has had outliers removed. Processed line data are available in *.gsf and ascii format, and processed bathymetry grids 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 IN2023_V05, titled "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 1). The voyage took place between June 28, 2023 and July 30, 2023 (AEST), departing from Hobart and returning to Hobart. The Simrad EK60 split beam echosounders for 18kHz 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 1500m, between Hobart and Sydney. All frequencies were logged continuously for the extent of the voyage. The 70 & 120 kHz frequencies were set to passive for periods of the voyage. Data are stored in *.raw, *.bot and *.idx format at CSIRO. There are 809 files totalling 68.4 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 sub bottom profiler data collected on RV Investigator voyage IN2023_V05, titled "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 1). The voyage took place between June 28, 2023 and July 30, 2023 (AEST), departing from Hobart and returning to Hobart. The Kongsberg SBP120 (sub bottom profiler) was used to acquire data containing the specular reflections at different sediment interfaces below the seafloor. The SBP120 provides a 3° by 3° angular resolution. The echosounder's frequency sweep range is from 2.5 to 7 kHz. The SBP120 was logged [continuously/sporadically] for the extent of the voyage. Data are stored in *.raw ( 2,896 files 65.7 GB) raw and *.seg (2,871 files 65.2 GB) segy formats at CSIRO. The segy format data had a real time processing stream applied, which applies gain, a gain correction, matched filter with replica shaping, an attribute calculation for instantaneous amplitude and time variable gain. 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 gravity data collected on RV Investigator voyage IN2023_V05, titled "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 1). The voyage took place between June 28, 2023 and July 30, 2023 (AEST), departing from Hobart and returning to Hobart. The gravity meter instrument is a MicroG Lacoste Air-Sea II. Data are stored in .ENV and .DAT data files at CSIRO. There are 14 files totalling 205 MB of raw data in this dataset. A wharf tie was not undertaken due to the sensor replacements, and malfunctions. Gravity data was acquired for adhoc periods throughout the voyage although due to continued errors, malfunctions and swapping of sensor hardware it is recommended this data not be published. The manufacturer advised the systems control module be replaced as a potential solution to malfunctions. This was carried out on the 3rd July 2023. The system was observed to similarly malfunction after a short period. Additional information regarding this dataset is contained in the GSM data acquisition and processing report.

This record describes the catch data from the Marine National Facility (MNF) RV Investigator voyage IN2023_V05, titled "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 1)." The voyage took place between 27 June 2023 and 29 July 2023 (AEST), departing from Hobart and returning to Hobart. The dataset contains catch data for specimens collected by Museums Victoria during the voyage. Records include species identification, counts and/or weights, and are linked to sampling metadata such as station number, location (latitude and longitude), depth, time, and gear type. These data provide a baseline for assessing species composition, abundance, and distribution, supporting long-term monitoring, research, and management of the southeast Australian marine ecosystem.

This record describes the CTD data collected on Investigator voyage IN2023_V05, titled: "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 1)." The voyage took place between June 27, 2023 and July 29, 2023 (AEST), departing from Hobart and returning to Hobart. Data for 62 CTD deployments were acquired using the Sea-Bird SBE9+V2 CTD unit #24 (S/N 1332), fitted with 36 twelve-litre bottles on the rosette sampler. Sea-Bird-supplied calibration factors were used to compute the pressures and preliminary conductivity values. CSIRO-supplied calibrations were applied to the temperature data. The data were subjected to automated QC to remove spikes and out-of-range values. The initial configuration of the CTD for casts #1-22 is shown in table 1 below. For casts #23-62 , the CDOM sensor on channel A4 was replaced by the Chelsea Aquatracka fluorometer (as indicated in table 1 below) due to suspiciously high readings obtained using the Wetlabs FLBBRTD fluorometer near the water surface. The Chelsea unit yielded a similar response, providing confidence that the unexpectedly high chlorophyll readings near the surface were not caused by sensor issues. The final conductivity calibration was based on a single deployment grouping. The final calibration from the secondary sensor had a standard deviation (SD) of 0.0013744 PSU, well within our target of ‘better than 0.002 PSU’. The standard product of 1-decibar binned averages were produced using data from the secondary sensors. The dissolved oxygen data (primary) calibration fit had a SD of 0.7868 μM. The agreement between the CTD and bottle data was good. Additional sensors include: SUNA Nitrate, Altimeter (Tritech PA500), Transmissometer (Wetlabs CStar), CDOM (replaced by Chealsea Aquatracka after cast #22), Chlorophyll-a, Scattering (Wetlabs ECO FLCDRTD) were installed on the auxiliary A/D channels of the CTD. The collected data were processed (quality-controlled), and subsequently archived by the CSIRO National Collections and Marine Infrastructure (NCMI) Information and Data Centre (IDC). Additional information regarding this dataset may be contained in the Voyage Summary and the Data Processing Report.

This record describes the End of Voyage (EOV) data archive from the Marine National Facility (MNF) RV Investigator voyage IN2023_V05, titled "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 1)." The voyage took place between June 27, 2023 and July 29, 2023 (AEST), departing from Hobart and returning to Hobart. Hydrology samples were collected from Niskin bottles sampled at various depths during Conductivity-Temperature-Depth (CTD) deployments. Parameters analysed were salinity, dissolved oxygen, phosphate, silicate, nitrate plus nitrite and ammonium. This dataset has been processed (quality-controlled), and archived at the CSIRO National Collections and Marine Infrastructure (NCMI) Information and Data Centre (IDC) in Hobart. Additional information regarding this dataset is contained in the Voyage Report and Data Processing Report.

This record describes the Underway (UWY) data collected from the Marine National Facility (MNF) RV Investigator voyage IN2023_V05, titled: "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 1)." The voyage took place between June 27, 2023 and July 29, 2023 (AEST), departing from Hobart and returning to Hobart. . Standard Underway data is continuously recorded, consisting of: (1) Navigation data (NAV): Latitude, Longitude, Speed, Heading, Course Over Ground, Gyros, and Doppler Log (dual GPS instrument). (2) Thermosalinograph (TSG): Water Salinity, Flow-Rate, Temperature, Fluorescence, pCO2 and Optode/Oxygen. (3) Atmospheric (MET): Humidity, Wind Speed and Direction (vane and ultrasonic), Radiometer/Sea Surface Temperature, Pyranometer/Solar Radiation, Photosynthetically Active Radiation (PAR), Air Temperature, Air Pressure, Rain, Ozone and Trace Gases (port and starboard instruments). The quality-controlled RV Investigator underway meteorological and SST data are supplied to the IMOS AODN and other global data repositories and distributors, and made available for satellite SST validation by the Australian Bureau of Meteorology (BoM). Near real-time, unprocessed data are available via the link "Visualisation tool for Underway Data." This dataset has been processed (quality-controlled), and archived by the CSIRO National Collections and Marine Infrastructure (NCMI) Information and Data Centre (IDC). Data are available at time intervals of 5 sec (NetCDF format), 5 sec, 10 sec, 1 min and 5 min (ASCII format). Note: not all variables are quality controlled; please check for existing QC flags in the datasets. Additional information regarding this dataset is contained in the Voyage Summary and/or the Data Processing Reports for this voyage.