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![Page 1: Measurements of acoustic backscatter and density of captive Atlantic cod with synchronized 300-kHz multibeam and 120-kHz split-beam echosounders 300-kHZ.](https://reader036.fdocument.pub/reader036/viewer/2022062518/56649f085503460f94c1d252/html5/thumbnails/1.jpg)
Measurements of acoustic backscatter and density of captive Atlantic cod with
synchronized 300-kHz multibeam and 120-kHz split-beam echosounders
300-kHZ多波束及 120-kHZ分割波束漁探機對於大西洋鱈之聲學反射及魚群密度量測
Gurshin, C. W. D., Jech, J. M., Howell, W. H., Weber, T. C., and Mayer, L. A. 2009.
ICES Journal of Marine Science, 66: 1303–1309.
981專題討論
Speaker : 黃星翰
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Fishery Echosounder
TS : target-strength ( dB)
sA : nautical area scattering coefficient ( m2 / m2)
Sv : volume backscattering strength ( dB)
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IntroductionIntroductionAcoustic vs. trawl surveyAcoustic vs. trawl surveyEchosounder seriesEchosounder seriesMultibeam echosounderMultibeam echosounder
Materials and methodsMaterials and methodsSample processingSample processingExperimentExperimentData analysisData analysis
ResultsResultsEK60 vs. EM3002EK60 vs. EM3002
DiscussionDiscussionResultsResults
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Introduction
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Fishery-acousticFishery-acoustic vs. Traditional trawl survey vs. Traditional trawl survey
•Fish density
•Biomass
•Spatial distribution
•Behaviour
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![Page 8: Measurements of acoustic backscatter and density of captive Atlantic cod with synchronized 300-kHz multibeam and 120-kHz split-beam echosounders 300-kHZ.](https://reader036.fdocument.pub/reader036/viewer/2022062518/56649f085503460f94c1d252/html5/thumbnails/8.jpg)
Multibeam echosoundersMultibeam echosounders
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ObjectiveObjective
Fewer application for demersal species
Not widely developed in the United States
Comparing split-beam and multibeam
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Materials and methods
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Atlantic codAtlantic cod
http://www.fishbase.org/Summary/SpeciesSummary.php?id=69
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Sample processingSample processing
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ApparatusApparatusSimrad EK60 120kHz splitbeam echosounder
Kongsberg EM3002 300kHz multibeam echosounder
7° Beam width 130°
23 mm copper Standar sphere 38.1 mm tungsten-carbid
8 - 10 m Calibrate depth 8 - 10 m
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Experimental setup
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Data analysisData analysis
Post-processing software : Echoview and Matlab
Statistical analysing software : SAS and R
AWC = EL - SL - 10 log10(ΩTXΩRX) + 2αR + 30 log10R+CSv = AWC - ( X - 20)10 log10(R) - 10 log10(cτ/2)
EL : echo levelSL : source levelα : attenuation coefficientΩTX : transmitting beam width
ΩRX : receiving beam widthR : range from the transducerC : calibration gain
Sv : volume-backscattering strength ( dB)X : collection of Awc
c : sound speed ( ms - 1)τ : pulse duration ( s)
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Sv for the EM3002
64dB dynamic range
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Threshold :- 36dB
Cod : 128
Cod : 23Cod : 66
Cod : 116
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Sv for the EK60Threshold :- 30dB
Cod : 128
Cod : 66
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Results
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14dB
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Date 25 June 26 June 27 June 27 June 28 June
Depth ( m) 6.5 7.2 8.0 11.0 8.8
LT ( cm) 80.7 81.1 82.1 82.1 82.9
n 128 116 66 66 23
Percentage 100 91 52 52 18
Total pings 1500 7140 1680 1800 5940
300kHz EM3002Sv ( dB ;95 % CI)
- 29.8(- 30.3, -
29.3)
- 31.7(- 31.9, -
31.5)
- 28.4(- 28.7, -
28.2)
- 29.1(- 29.4, - 28.
8)
- 39.7(- 40.3, - 39.
1)
300kHz EM3002Percentage
100 65 138 117 10
120kHz EK60Sv ( dB ;95 % CI)
- 29.4(- 30.0, -
28.8)
- 26.5(- 26.9, -
26.2)
- 23.6(- 24.2, -
23.1)
- 26.4(- 26.9, - 25.
8)
- 38.8(- 40.0, - 37.
8)
120kHz EK60Percentage
100 195 380 200 11
TSa - 26.9 - 26.8 - 26.7 - 26.7 - 26.6
Expectedb Sv at 120kHz
- 25.7 - 26.1 - 28.4 - 28.4 - 32.9
TSa = 20 log (LT) - 65 (Rose and Porter, 1996) at 120kHz, where LT is the total length (cm).bSv = TS + 10 log (N/V) , where N is the number of cod in the sampled volume V.
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6 dB7 dB
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Discussion
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SSvv
1. Random and homogeneous distribution of target
2. Constant fish orientations(assuming linearity in echo-
integration)
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SensitivitySensitivity
high low
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ImprovementImprovementLimitation 64 dB dynamic range Split-beams detection in the athwartships direction only Nearfield range of ~7m
Simrad ME70Adjustable beam width ( 2.2 - 20°)Split-beam operating at multiple frequencies
Calibration of all beams Single-target detections TS estimations Quantification of the effect of different incidence angle and
overlapping beams on volume-backscatter measurements
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Thanks for your attention