Marine and fisheries acoustics and sub surface mapping
Even though 70% of Australia’s territory is underwater, only 25% of Australia’s EEZ has been mapped with multibeam.
A sample of fish collected with a beam trawl.
Marine Acoustics - Seafloor Mapping
Investigator can map the seafloor in 3D and can do it faster and with greater resolution than our previous vessel, Southern Surveyor. This provides the capability to map the entire Exclusive Economic Zone (EEZ) of Australia.
Investigator has two mulltibeam swath bathymetry mapping systems, one designed for deep water (EM122 – works best from 300-400m to full ocean depth) and one designed for shallow to mid depth water (EM710 – works best down to 600-700m). The shallow to mid depth water system is particularly suited to the continental shelf and upper slope while the deep water system is designed for the deeper waters of our surrounding oceans and seas. The SBP120 sonar sub-bottom profiler complements the bathymetric mapping systems by providing a shallow vertical ‘seismic’ section through seafloor sediments.
- Full ocean depth multibeam (primarily bathymetry and bottom identification).
- Operating frequency: 12kHz.
- Number of beams: 288.
- Horizontal resolution: 1 x 1 degree.
- Maximum width: 6 x waterdepth/ 30 km/ 143 degrees.
- Depth range: 50-11,500m.
- Shallow to mid depth (maximum 2000m) multibeam (primarily bathymetry and bottom identification).
- Operating frequencies: 70-100kHz.
- Number of beams: 400.
- Horizontal resolution: 0.5 x 1 degree.
- Maximum width: 5.5 x waterdepth/ 2300m/ 140 degrees.
- Depth range: 3–2,000m (ideal range down to 600-700m).
- Sub-bottom profiler (sediment layers and buried objects).
- Operating frequencies: 2 – 8kHz and 12kHz.
- Horizontal resolution: 3 x 3 degree.
- Depth penetration depends on sediment type, but up to tens of metres.
- Single beam bathymetry and underwater communications such as acoustic releasers and pingers.
- Operating frequency: 12kHz.
- Deep (to 700m) current profiler.
- Mid depth (to 400m) current profiler.
ITI Net Monitoring System
- Trawl net monitoring.
- Linked to the SH90 for targeted trawling.
- Provides location of deployed instruments relative to the ship.
Dual Axis Doppler Log
- Speed and direction of the ship relative to the water.
Sound Velocity Probe
- Sound velocity at the depth of transducers – used in multibeam beam forming.
- 4 hull mounted hydrophones for ship self noise monitoring and underwater acoustics.
Investigator can map below the seafloor giving researchers valuable information about the geological structure of the seabed.
The vessel has two sub-surface mapping systems – a sub-bottom profiler and seismic survey system.
The sub-bottom profiler emits an acoustic signal that penetrates up to 25 m in sand and up to 100 m in loose sediments. The return signal images the layers of mud, sand and rock below seabed. The system is designed for optimal returns in rough terrain.
Kongsberg SBP120 sub-bottom profiler.
Operating frequency: 2-8kHz and 12kHz.
Transmit array: fan of narrow beams across track.
Terrain adapted beam steering.
The fisheries acoustics consist of a scientific echo sounder for estimating fish abundance and plankton, a high definition fish finding sonar for finding and identifying fish and a scientific multibeam echo sounder for water column analysis.
Scientific echo sounder
The Kongsberg EK60 singlebeam scientific echo sounder simultaneously uses six discrete echosounder frequencies with a high dynamic range, and can be used for describing individual targets as well as large numbers of targets distributed through a volume of water.
Fish finding sonar
The fish finding sonar is designed to locate a range of fish including those located near the surface and close to the bottom without the need for passing over the fish. It is interfaced with the ITI trawl system.
Scientific multibeam echo sounder
The scientific multibeam echo sounder combines the large and flexible sampling volume of the multibeam swath with the accuracy of the quantitative scientific echo sounder. It provides a configurable wide fan of stabilised and calibrated beams for biomass estimation and fish school characterisation.
Simrad EK60 scientific echo sounder system
- Singlebeam, multifrequency system.
- Operating frequencies: 18kHz, 38kHz, 70kHz, 120kHz, 200kHz, 333kHz.
Simrad SH90 Fish finding sonar
- 360 degree, omni sonar.
- Operating frequency: 114kHz.
Simrad ME70 Scientific multibeam echo sounder
- Multibeam, variable frequency echosounder.
- Operating frequencies: 70-120kHz.
- 140 degree maximum total swath width.
- 3 to 45 stabilised beams.
Updated: 15 July 2015