The University of Washington, working with NOAA's Northwest Fisheries Science Center (NWFSC), recently retrieved a BioSonics DT-X SUB split beam echosounder after a 1-month deployment in northern Admiralty Inlet, WA. The study location is a proposed Snohomish Public Utility District tidal energy demonstration project site.
The BioSonics DTX-SUB is an autonomous scientific echosounder packaged in a subsea pressure housing with integrated power management and data storage systems. "When it's down there, collecting data, it's completely self-contained. There's no line to the surface, no signal to the surface. It's entirely contained in just what you see here," said Jim Thomson, Oceanographer with the University of Washington. The DT-X SUB is being used to detect, categorize, and enumerate pelagic fish, invertebrate, and marine mammal species at the proposed site. The intent is to allow marine hydrokinetic (MHK) site and device developers to install tidal turbines in suitable locations while minimizing behavioral effects on aquatic organisms.
DT-X SUB and other remote sensors affixed to Seaspider tripodAfter programming the echosounder configuration and duty cycle at the surface, the echosounder was deployed to the sea floor affixed to a Seaspider tripod instrument mount. The programmable DT-X SUB system automatically collected and logged water column backscatter data from split beam transducers throughout the month long deployment. The scientific echosounder was programmed to collect data every other hour in a 10% operational duty cycle, alternating between pinging and sleep modes. This duty cycle maximized temporal coverage and extended battery life for the duration of the deployment. Last week, the system was retrieved using acoustic releases and the data files were downloaded for processing of fish abundance, distribution, and behavior information.
BioSonics has considerable experience in providing submerged, cabled observatory echosounder systems as well as fully-automated hydroacoustic monitoring systems. The DT-X SUB was developed based on this experience and further advancement of BioSonics automated echosounder technology. The DT-X SUB is now commercially available to be used by national and international institutions as a quantitative remote sensing instrument.