Seeing further: Broadband acoustics for improved measurements of demersal fishes.
Illustration in article by Tommy Thorseth
SEEBED is a fishery technology research project for the Research Council of Norway. Institute of Marine Research (IMR) leads the project, with partners SIMRAD (Norway), CMR (Norway), WHOI (USA) and NMFS (USA).
The primary objective of this project is to develop and implement acoustic methods of detecting and characterising organisms that are close to the seabed. This will be achieved via the sub-objectives:
- Use broadband pulses to see closer to the seabed than is possible with single-frequency pulses and to separate fish and seabed echoes using spectra and amplitude contrasts
- Use broadband pulses to improve target characterisation via higher-resolution frequency spectra
- Implement new algorithms and methods in an acoustic analysis software package for scientific and fishery use
The field of fisheries acoustics has two major long-standing methodological problems: the difficulty in resolving fish that are very close to the seabed from the seabed itself (that is, the deadzone problem), and accurate species characterisation or classification. These problems limit the usefulness of acoustic techniques for demersal ecosystems. These problems can be reduced through the use of broadband acoustic techniques, which give considerably higher range resolution and finer frequency spectra than is possible with conventional multi-frequency echosounder systems. Accordingly, this project will apply the advantages of broadband pulses to allow us to see further towards the seabed. Better detection of single fish close to the seabed will yield high quality fish track data which will be used to develop and enhance fish characterisation algorithms.
CMR contribute with implementation of the broadband processing methods developed in the project. These methods are implmented in the LSSS post-processing system by CMR, the original and current co-developers of LSSS (along with IMR).
Institute of Marine Research / RCN