Aquat. Living Resour.
Volume 13, Number 5, September-October 2000Shallow Water Fisheries Sonar
|Page(s)||395 - 401|
|Published online||15 September 2000|
Detection of migratory herring in a shallow channel using 12- and 100-kHz sidescan sonars
Acoustical Oceanography, Institute of Ocean Sciences, 9860 W. Saanich Rd., B.C. V8L 4B2 Canada
2 LIC Engineering A/S, Ehlersvej 24, DK-2900 Hellerup, Denmark
Accepted: 24 March 2000
A hydroacoustic monitoring program for migratory herring was conducted in Drogden Channel, near Copenhagen, Denmark, beginning in June, 1996. Using installations of 100-kHz sidescan sonar oriented across the channel, herring schools were observed at ranges up to 500 m in water depths of 10–14 m. In October 1997, this effort was supplemented with a 12-kHz sidescan mounted on a motorized tripod allowing azimuthal sector scanning. This 12-kHz sidescan was able to detect herring schools up to a 1200-m range. Two examples are examined to assess the limits of herring school detectability and the feasibility of abundance estimation. In both cases, herring schools are detectable by their transience and up to 20 dB signal excess relative to the nominally stationary background reverberation, dominated by seabed backscattering. Attempts are made to extract quantitative abundance estimates using methods based on school size and density, and through quantitative echo-integration. Acoustic ray tracing was found to be useful in interpreting the results, and in particular modeling boundary-reflection focusing as a potential source of positive bias in herring abundance estimates.
Key words: herring schools / sidescan sonar / acoustic ray-tracing
© Elsevier, Inra, Ifremer, Cemagref, Ird, Cnrs, 2000
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.