LOW POWER MULTI-FREQUENCY SONAR FOR NEAR REAL TIME LONG-TERM OBSERVATIONS OF VOLUME BACKSCATTER
Long time series of continuous data from moored acoustic instruments offer a low-cost method to study ecosystem changes by monitoring the behaviour and abundance of fish and zooplankton in the ocean and lakes. Calibrated sonars with several frequencies allow some information about species composition and abundance to be deduced from acoustic backscatter data. This presentation describes an improved low power, battery-operated sonar with up to four frequencies capable of autonomously collecting data at high temporal and spatial resolution for periods of several months. The procedures used to calibrate the instrument are described. To illustrate the potential of such observations, data from two installations on the VENUS observatory in coastal British Columbia are discussed. The effects of seasonal and year-to-year variations are shown in a several-month segment of a six-year time series collected by a 200 kHz sonar mounted in Saanich Inlet. Data from 6 month deployment of a 3-frequency instrument in the Strait of Georgia shows an example of the additional information that can be obtained from simultaneous measurements at several frequencies.
Lemon, D. D., ASL Environmental Sciences Inc., Canada, firstname.lastname@example.org
Dewey, R. K., University of Victoria, Canada, email@example.com
Clarke, M. R., ASL Environmental Sciences Inc , Canada, firstname.lastname@example.org
Time: 16:00 - 18:00
Location: Poster/Exhibit Hall
Presentation is given by student: No