scholarly journals An operational system for automatic school identification on multibeam sonar echoes

2009 ◽  
Vol 66 (5) ◽  
pp. 935-949 ◽  
Author(s):  
Vasilis Trygonis ◽  
Stratis Georgakarakos ◽  
E. John Simmonds
Keyword(s):  
Three Dimensional ◽  
Beam Width ◽  
Multibeam Sonar ◽  
Operational System ◽  
Fish Schools ◽  
Fish School ◽  
School Identification ◽  
Detection And Identification ◽  
Spatio Temporal ◽  
Sonar Echoes

Abstract Trygonis, V., Georgakarakos, S., and Simmonds, E. J. 2009. An operational system for automatic school identification on multibeam sonar echoes. – ICES Journal of Marine Science, 66: 935–949. A system for identifying and tracking fish schools is demonstrated, based on the analysis of multibeam sonar data obtained by a Simrad SP90 long-range sonar. Fish-school detection and identification techniques are similar to those commonly used for vertical echosounders, further enhanced with innovative processing algorithms applied to successive multibeam echograms, increasing the certainty that the identified objects are fish schools. Additionally, analysis of school dynamic parameters facilitates the classification of targets into certain groups, here discriminating the fish aggregating device-natant fish complex from tuna. Statistical analysis of selected tracks quantifies the spatio-temporal variability of the school descriptors, which are used retrospectively to select appropriate analysis thresholds. The algorithms are implemented in an acquisition, visualization, and processing software platform that is flexible regarding sonar characteristics (beam width and number of beams) and can be extended easily to track school echotraces in a three-dimensional mode.

scholarly journals Corrections of fish school area and mean volume backscattering strength by simulation of an omnidirectional multi-beam sonar

2018 ◽  
Vol 75 (4) ◽  
pp. 1496-1508 ◽  
Author(s):  
Vasilis Trygonis ◽  
Zacharias Kapelonis
Keyword(s):  
Three Dimensional ◽  
Simulated Data ◽  
Beam Width ◽  
Dependent Manner ◽  
Cross Sectional ◽  
Density Estimates ◽  
Fish Schools ◽  
Fish School ◽  
Backscattering Strength ◽  
The Difference

Abstract Fish school descriptors extracted from omnidirectional multi-beam data are biased due to beam width-related effects, and echotraces are distorted in a range-dependent manner that is a function of transducer intrinsic properties, as well as fish school characteristics. This work investigates a simulation approach that models the three-dimensional insonification of fish schools by an omnidirectional fishery sonar in order to assess the bias in measuring two key morphometric and energetic descriptors, namely the horizontal cross-sectional area of schools and their mean volume backscattering strength. Simulated fish schools of different sizes and backscattering properties were insonified at various ranges from the multi-beam transducer, outputting volume backscattering strength echograms. The simulated data were used to develop empirical models that correct the examined descriptors using only information extracted from the observed echotraces. Depending on the difference between the observed mean volume backscattering strength of a school and the echogram processing threshold, mean absolute percentage errors in measured area and volume backscatter reduced from 100.7% and 79.5% to 5.2% and 6.4%, respectively. The mean volume backscattering strength of a school is a key parameter for obtaining fish density estimates, and the results highlight the need for descriptor corrections to better interpret the multi-beam data.

Multibeam sonar image processing and three‐dimensional analysis of fish schools

1998 ◽  
Vol 103 (5) ◽  
pp. 2939-2939 ◽  
Author(s):  
Chafiaa Hamitouche ◽  
Valerie Fracasso ◽  
Carla Scalabrin
Keyword(s):  
Image Processing ◽  
Dimensional Analysis ◽  
Three Dimensional ◽  
Multibeam Sonar ◽  
Fish Schools ◽  
Sonar Image

Acoustic Measurement of Fish Schools Using Array Phase Information

1987 ◽  
Vol 44 (9) ◽  
pp. 1544-1550 ◽  
Author(s):  
G. L. Thomas ◽  
Darrell R. Jackson
Keyword(s):  
Horizontal Plane ◽  
Beam Width ◽  
Target Strength ◽  
Acoustic Measurement ◽  
Phase Information ◽  
Fish Schools ◽  
Fish School ◽  
Blue Whiting ◽  
Beam Directivity ◽  
Better Than

Array phase information on the azimuth and elevation of fish schools allows for beam directivity corrections of target strength, determinations of school depth, and tracking of school movements. When corrected for beam pattern losses, the target strength of blue whiting (Micromesistious poutassou) and rockfish (Sebastes spp.) schools increased approximately 3 dB. The vertical placement of fish schools with the side-scanning split-beam sonar agreed with the fish school depths observed with an echosounder. Split-beam phase was used to track blue whiting schools in the horizontal plane with azimuthal accuracy considerably better than the 3-dB beam width (approximately 20°).

scholarly journals A method for reducing uncertainty in estimates of fish-school frequency response using data from multifrequency and multibeam echosounders

2009 ◽  
Vol 66 (6) ◽  
pp. 1155-1161 ◽  
Author(s):  
Laurent Berger ◽  
Cyrille Poncelet ◽  
Verena M. Trenkel
Keyword(s):  
Frequency Response ◽  
Beam Width ◽  
Multibeam Echosounder ◽  
Fish Schools ◽  
Fish School ◽  
Geographic Coordinate System ◽  
Backscattering Strength ◽  
Adaptive Thresholds ◽  
Exact Position ◽  
Using Data

Abstract Berger, L., Poncelet, C., and Trenkel, V. M. 2009. A method for reducing uncertainty in estimates of fish-school frequency response using data from multifrequency and multibeam echosounders. – ICES Journal of Marine Science, 66: 1155–1161. Fish schools can be insonified simultaneously with multifrequency echosounders (e.g. Simrad EK60s) and a multibeam echosounder (e.g. Simrad ME70). This paper presents a method for combining these data to improve estimates of the relative frequency response r(f) of fish schools. Values of r(f) are now commonly used to classify echoes in fishery surveys. The data from the roll- and pitch-stabilized, high-resolution ME70 are used to correct beam-width effects in the multifrequency EK60 data. First, knowing the exact position and orientation of the transducers and the position of the vessel, the echoes are placed into a common geographic coordinate system. Then, the EK60 data are rejected if they do not include a significant percentage of the fish school imaged with the multibeam echosounder. Echoes that exceed the overlap threshold are used to estimate the r(f). The proposed method is applied to simulated and actual data for sardine and mackerel schools in the Bay of Biscay to estimate their r(f) values. The results for different overlap thresholds are compared with the results of a different method, one that uses adaptive thresholds on volume-backscattering strength Sv. The proposed method reduces uncertainty in estimates of r(f) for schools with an overlap of greater than 80%, and it outperforms the Sv-thresholding technique.

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

1999 ◽  
Vol 56 (1) ◽  
pp. 6-12 ◽  
Author(s):  
François Gerlotto ◽  
Marc Soria ◽  
Pierre Fréon
Keyword(s):  
Three Dimensional ◽  
Two Dimensions ◽  
School Structure ◽  
Fish Behaviour ◽  
New Approach ◽  
Multibeam Sonar ◽  
Fish Schools ◽  
Fisheries Acoustics ◽  
Working Frequency ◽  
School Classification

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.

MODELING THE DISTRIBUTION OF FISH SCHOOLS IN THE BERING SEA: MORPHOLOGICAL SCHOOL IDENTIFICATION

1994 ◽  
Vol 8 (2) ◽  
pp. 177-194 ◽  
Author(s):  
Gordon Swartzman ◽  
Werner Stuetzle ◽  
Kristin Kulman ◽  
Nuan Wen
Keyword(s):  
Bering Sea ◽  
Fish Schools ◽  
School Identification ◽  
Distribution Of Fish ◽  
The Bering Sea
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