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TRAINING

We offer a one-week course in fisheries acoustics covering basic principles of sound propagation and reflection underwater, surveying equipment and density estimation (see course outline below) which can be given anywhere in the Southern African region. To date, two such courses have been given in Swakopmund, Namibia, to fisheries scientists and technicians from the region. Both included practical calibration exercises at sea on a local research vessel (below). The course can be tailored to your special needs to include, for example, survey design and error analysis, and to give greater emphasis on specialized topics such as the estimation of target strength and acoustic methods of target identification and classification.

In addition, we offer practical hands-on training in fisheries acoustics during surveys and experimental cruises, with emphasis on one-on-one interaction. We are also able to assist and train researchers in the planning and design of surveys and associated experimental work, and in the processing of the data and the analysis and reporting of the results.

FRS Acoustic Course: Outline

1. Introduction and basic principles of sound
   Introduction
   Basic principles of sound
   Echo-sounder considerations
   Decibel units
   

2. Generation of sound – the transmitter
   The transmitter
   Choice of operating frequency
   Pulse duration and receiver bandwidth considerations
   Ping interval
   

3. Generation of sound – transducers
   Magnetostrictive transducers
   Ceramic transducers
   Source level
   Intensity and beam patterns
   Efficiency
   Transducer bandwidth and Q factor
   Nearfield and farfield
   Directivity factor and directivity index
   The equivalent ideal beam angle
   

4. Propagation of sound underwater
   Attenuation
   Refraction
   Reflection
   

5. Factors affecting target detectability
   Noise
   Sources of acoustic noise
   Hydrodynamic noise
   Machinery noise
   Reverberation
   Ambient noise
   Refraction
   Reflection from other targets
   Noise reduction
   

6. Echo-sounders, sonars and netsounders
   Echo-sounders
   Sonars
   Side-scan sonars
   Net sounders
   

7. Introduction to fish target strength
   Target strength
   Fish size and target strength dependence
   The effects of fish tilt angle
   

8. Determination of fish target strength
   Measurements on single dead or captive fish
   Cage experiments
   In-situ methods
   Single target detectors
   

9. Determination of fish density
   Echo integration theory
   The area back-scattering coefficient
   Echo integrators
   

10. Calibration
    The on-axis sensitivity
    The reciprocity technique
    The calibrated hydrophone
    The standard sphere method
    The TVG function
    The equivalent beam angle
    

    Practical work sessions to introduce participants to:

11. General Operation Of SIMRAD Echo Sounders
    The menu system
    What you should touch
    What you shouldn’t touch
    

12. Echo Integration Analysis Software
    SONARDATA ECHOVIEW