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Monitoring fish migration in Rivers. Helge Balk Department of Physics. University of Oslo. River Tana. River Tana. Tornio (Se/Fi). River Reisa (north Norw.). River Fischa in Austria. 4-Ch TVG. Echosounder in the river. Amplitude Detector. 1 size correction. Phase detector.

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Monitoring fish migration in rivers
Monitoring fish migration in Rivers

Helge Balk

Department of Physics. University of Oslo.







Echosounder in the river

4-Ch

TVG

Echosounder in the river

Amplitude

Detector

1 size correction

Phase detector


What we can do to increase the detection probability

Estimate the DPF

Reduce the variation in the DPF

Site selection

Bottom modification

Surface modification

Guide fish

Opening angle

Sound frequency


If we detect a fish, What does it mean?

Echo sounder

Fish detection software

?


Interpretation: DPF, noise and time expansion

Echo sounder

Fish detector

Interpreter

Meaningful statistics

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


What did we cover?

Interpretation: Area expansion

!

Echo sounder

Fish detector

Interpreter

Meaningful statistics!

Where did the fish pass?

Index or total run?


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?


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?


x


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