From two dimensions to three: the use of multibeam sonar for a new approach in fisheries acoustics

We present a methodology applying multibeam sonar for three-dimensional (3D) observation of fish schools that enhances the conventional use of vertical scientific echo sounders. The sonar we employ has 60 beams of 1.5° each. Its working frequency is 455 kHz. It is applied on a vertical plan normal to the vessel route, observing from the surface line to the bottom with a range set to 100 m. The sampled volume is 14 times larger than the volume observed with vertical echo sounding. The contribution of this new methodology to fisheries acoustics is detailed for school classification, internal school structure, spatial distribution of schools, fish behaviour, and biomass estimates. For each of these points, we present some preliminary results with the aim of defining the real progress in fisheries acoustics research as a result of 3D acoustics. Finally, we present a list of technical and methodological improvements that we are developing in order to make multibeam sonar fully adapted to fisheries acoustics.

[1]  Alain Hillion,et al.  Narrowband acoustic identification of monospecific fish shoals , 1996 .

[2]  W. C. Leggett,et al.  Hydroacoustic Signal Classification of Fish Schools by Species , 1988 .

[3]  S. Georgakarakos,et al.  Artificial neural networks as a tool for species identification of fish schools , 1996 .

[4]  O L E A Rv,et al.  Underwater acoustics in marine fisheries and fisheries research , 1997 .

[5]  Pierre Fréon,et al.  Dynamics of pelagic fish distribution and behaviour : effects on fisheries and stock assessment , 1999 .

[6]  T. Bahri,et al.  Spatial structure of coastal pelagic schools descriptors in the Mediterranean Sea , 2000 .

[7]  David G. Reid,et al.  Image Analysis Techniques for the Study of Fish School Structure from Acoustic Survey Data , 1993 .

[8]  Jacques Masse,et al.  Acoustic detection of the spatial and temporal distribution of fish shoals in the Bay of Biscay , 1993 .

[9]  E. Ona,et al.  Avoidance reactions of herring to a survey vessel, studied by scanning sonar , 1988 .

[10]  Ole Arve Misund,et al.  Swimming behaviour of fish schools in the North Sea during acoustic surveying and pelagic trawl sampling , 1992 .

[11]  E. John Simmonds,et al.  Acoustic survey design and analysis procedure : a comprehensive review of current practice , 1992 .

[12]  M. L. Somers,et al.  An experimental survey of a herring fishery by long-range sonar , 1973 .

[13]  Pierre Fréon,et al.  Changes in school structure according to external stimuli: description and influence on acoustic assessment , 1992 .

[14]  Pierre Fréon,et al.  Some elements on vertical avoidance of fish schools to a vessel during acoustic surveys , 1992 .

[15]  Marc Soria.  Structure et stabilité des bancs et agrégations de poissons pélagiques côtiers tropicaux : Application halieutique , 1994 .

[16]  Pierre Fréon,et al.  Analysis of vessel influence on spatial behaviour of fish schools using a multi-beam sonar and consequences for biomass estimates by echo-sounder , 1996 .

[17]  P. Petitgas.  Geostatistics for fish stock assessments: a review and an acoustic application , 1993 .

[18]  Noël Diner,et al.  MOVIES-B: an acoustic detection description software. Application to shoal species' classification , 1993 .

[19]  Pierre Petitgas,et al.  Spatial organization of pelagic fish: echogram structure, spatio-temporal condition, and biomass in Senegalese waters , 1996 .

[20]  Pierre Fréon,et al.  Consequences of fish behaviour for stock assessment , 1993 .

[21]  Peter J. Diggle,et al.  Statistical analysis of spatial point patterns , 1983 .