monitoring migrating fish in rivers
DESCRIPTION
Monitoring migrating fish in rivers. Helge Balk Department of Physics. University of Oslo. Special tools for rivers. Introduction. Sonar5 and river work. Analysis chain. TS. Discussion. Acoustics in rivers. DPF. Meaning of an observation. Interpretation. TS and positioning. - PowerPoint PPT PresentationTRANSCRIPT
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Monitoring migrating fish in rivers
Helge Balk
Department of Physics. University of Oslo.
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Acoustics in rivers
Discussion
Sound propagation
Special tools for
rivers
Analysis chain
Introduction
Noise
Meaning of an observation
Time and area expansion
Interpretation
Sonar5 and river work
Noise and DPF
Observations in Tana and Rimov
Waves Current,
stones, rainHydrophone experiments
TS
DPF
TS and positioning
Measurements in Fisca (Au)
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Sonar5 tools for river workSonar5 tools for river work
Current profile Bottom profile Exact target positioning Transducer positioning Diurnal coverage
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Position diagram can present the Position diagram can present the water currentwater current
Important to see whether a track
moves against the current or not
Popup menu
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Position diagram Position diagram exact position exact position and bottom and bottom profileprofile
Draw bottom with a pencil Move or tilt transducer Raise and lower water level Measure distances
Popup menu
Demonstrate it?
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Description of the sonar file Description of the sonar file
Control the current, bottom profile, and
transducer placement
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Sound propagationSound propagation
Estimate sound propagation features
Estimate “true” target position and beam behaviour
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Site calculator Site calculator
Assist in describing the
transducer position
Originally developed to find the same position each year in River
Tana
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Diurnal coverage and file Diurnal coverage and file informationinformation
Advanced file open dialog
looks into the files and estimate diurnal
coverage
Individual description and
photo from each file can
be presented as well
Aspect correction and fish sizingAspect correction and fish sizing
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River analysis chain in River analysis chain in
Sonar5-proSonar5-pro
Echo sounder
transducer position and
alignment
River co-ordinates
x,y,z
Size correction
Track Aspect angle detection
TS / aspect / length regressions
beam mapping
Cross filter
detector
Cross filter tracker
Feature extraction
Classification
10,3,4,7
Split and rule
Focus on detecting as many echoes as possible from all targets. Fish, debris and stones
Focus on generating tracks from all targets, not only fish
Classify tracks
Interpretation
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Acoustics in rivers
Discussion
Sound propagation
Special tools for
rivers
Analysis chain
Introduction
Noise
Meaning of an observation
Time and area expansion
Interpretation
Sonar5 and river work
Noise and DPF
Observations in Tana and Rimov
Waves Current,
stones, rainHydrophone experiments
TS
DPF
TS and positioning
Measurements in Fisca (Au)
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If we detect a fish, What does it If we detect a fish, What does it mean?mean?
Echo sounder
?
Fish detection software
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Interpretation: DPF, noise and time Interpretation: DPF, noise and time expansionexpansion
Measure noise level as a function of time and range over years
Apply noise level as an overall fish size threshold
Use noise level to correct the number of fish within each size group
Apply time expansion to find the total fish abundance estimate
Noise level
Threshold
Intensity
1 2 3 4 5 6 7 8 9 10 Time
High noiselevel
Halt inrecording
High noiselevel
Echo sounder
Fish detector Meaningful
statistics
Interpreter
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Interpretation: Interpretation: Area expansionArea expansion
Echo sounder Meaningful
statistics!
Covered areaUncovered area
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0
2
3
2
1
What did we cover?
Where did the fish pass?
Index or total run?
Fish detector
Interpreter
!
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Acoustics in rivers
Discussion
Sound propagation
Special tools for
rivers
Analysis chain
Introduction
Noise
Meaning of an observation
Time and area expansion
Interpretation
Sonar5 and river work
Noise and DPF
Observations in Tana and Rimov
Waves Current,
stones, rainHydrophone experiments
TS
DPF
TS and positioning
Measurements in Fisca (Au)
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What is the main problem with fish What is the main problem with fish counting in rivers… counting in rivers…
Noise ,Noise and Noise
What can be worse than noise?
Variable noise
Why?
Variable detection probability
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Detection Probability Function Detection Probability Function (DPF )(DPF )
Varies with Time Range
More likely to detect a large fish than a small fish a fish when the noise level is low a fish in the centre of the beam a fish passing normal towards
the transducer a fish if the cross section
coverage is increased
Noise as a function of range
Noise as a function of time
Rimov experiment, water current Rimov experiment, water current
B
A
C
D2.65 m
0 m 5.8m 9m
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Rimov experiment, water currentRimov experiment, water current
Observed:Observed:
Increased reverberation Increased reverberation Shift in target positionShift in target positionreduced stability in TS estimatesreduced stability in TS estimates
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Rimov experiment, Noise from Rimov experiment, Noise from stones and wavesstones and waves
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Rimov experiment, Noise from Rimov experiment, Noise from waveswaves
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Acoustics in rivers
Discussion
Sound propagation
Special tools for
rivers
Analysis chain
Introduction
Noise
Meaning of an observation
Time and area expansion
Interpretation
Sonar5 and river work
Noise and DPF
Observations
In River Tana
In RimovHydrophone experiments
TS
DPF
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Strange observations in River TanaStrange observations in River Tana
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Strange observations in River TanaStrange observations in River Tana
We observed that the target was
visible
Until it was laying on the bottom
On the outside of the boat
from the moment it touched surface
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Strange observations in River TanaStrange observations in River Tana
a) meter 6.5 12 27. 42 52 m.b) Depth 2.25 2.7 3.0 3.5 3.5 m.c) beam 0.45 0.84 1.89 2.93 3.63 m.
Depth (y)(m)0
1.00
2.00
3.00
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Summary of observations in Summary of observations in River TanaRiver Tana
1. Target observed far outside the theoretical beam
2. Target strength observed to increase with range
3. No clear beam pattern was found at any tested range
4. Vertical phase reading seemed corrupted
5. Horizontal phase reading seemed fine
6. Returned echo length observed to be 1.5 times the transmitted pulse-length
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Strange observations in RimovStrange observations in Rimov
0 5.14 7 10 Range(m) 0.36 0.49 0.7 Beam thickness (m)
0 0.25 0.50 0.75 1.00 1.25 1.50
Looked like a second beam
under the existing beam
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Summary of observations in RimovSummary of observations in Rimov1. Target observed outside the theoretical beam
2. The target behaved normally within the position of the theoretical beam
3. A second beam was observed under the first beam
4. The under beam’s intensity show the same profile as the main beam, but with weaker echo intensity
5. The under beam’s angle estimates show a narrower opening angle than the main beam
6. A transition region was observed between the two beams at shorter range. At longer range the two beams melted together into one wide beam
7. Echo-pulse-length did not differ from the transmitted pulse-length
8. The transducer depth and tilt influenced the phenomenon
9. The phenomenon depended on the transducers opening angle
10. The phenomenon varied with range
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What causes the observed What causes the observed phenomena?phenomena?
Refraction and reflection Sound channels and waveguides Image interference Dipole effect Side lobe effect
Direct sound measurementsDirect sound measurementsShow separate presentation
Direct sound measurementsDirect sound measurements
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Acoustics in rivers
Discussion
Sound propagation
Special tools for
rivers
Analysis chain
Introduction
Noise
Meaning of an observation
Time and area expansion
Interpretation
Sonar5 and river work
Noise and DPF
Observations in Tana and Rimov
Waves Current,
stones, rainHydrophone experiments
TS
DPF
TS and positioning
Measurements in Fisca (Au)
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River Fischa in River Fischa in AustriaAustria
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Target detection possibleTarget detection possible
Parametric SED Crossfilter SED
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Lifting target from bottom to Lifting target from bottom to surface. Positioning and sizing?surface. Positioning and sizing?
SED, TSc versus ping AMP, TSu versus ping
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10 meter long salmon10 meter long salmonobserved observed
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Acoustics in rivers
Discussion
Sound propagation
Special tools for
rivers
Analysis chain
Introduction
Noise
Meaning of an observation
Time and area expansion
Interpretation
Sonar5 and river work
Noise and DPF
Observations in Tana and Rimov
Waves Current,
stones, rainHydrophone experiments
TS
DPF
TS and positioning
Measurements in Fisca (Au)
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What can we do with the detection What can we do with the detection probability probability
Site selection
Bottom modification
Surface modification
Guide fish
Opening angle
Sound frequency
Estimate the DPF
Reduce the variation in the DPF
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Can we estimate TS in a river? Can we estimate TS in a river?
Spherical or cylindrical spreading? Corrupted vertical angular measurements? Additive noise? Can we compensate for swimming motion?
Can we compensate for fish aspect?
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Can we estimate TS in a river?Can we estimate TS in a river?
Alternative methods to establish the size?
Beam intensity mapping?
Apply reference targets?
Multiple narrow beams?
Multiple frequencies?
Aspect detection and correction?
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x
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ENDEND
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Tracking principlesTracking principles Split and rule
1. Focus on detecting as many echoes as possible from all targets. Fish, debris and stones
2. Focus on generating tracks from all targets, not only fish
3. Classify tracks
4. Interpret counting result
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Fish counting
Interpretation
Track size estimation
Noise level analysis
Time expansion
Area expansion
Analysis
Crossfilter tracking
Track classification
Pre-analysis Noise level Bottom line detection
Cross filter SED detection
Preparation
Bottom profile
Study test recordings
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Pre-Analysis Pre-Analysis
Use “vertical” bottom detection to avoid analysis of the outer noisy range.
Low-pass filter to reduce noise Cross-filter detector to detect single targets
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AnalysisAnalysis
Manual tracking and classification, Too subjective? Cross filter tracking Automatic or manual classification Fish baskets, track storing and track sorting Track statistics
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OutlineOutline Noise
Experiments with rain, waves, stones, current… Detection probability function
Sound propagation observations Refraction and reflection Tana and rimov phenomenon Direct hydrophone measurements
What about target strength? Observations in River Fischa (Au)
Interpretation of results Our analysis procedure for rivers What we have learned about tracking
Split and rule Manual tracking is subjective and time consuming Amp echogram is important
Tools supporting river applications in Sonar5-Pro Discussion