A General Guide for Deriving Abundance Estimates from Hydroacoustic Data





Data Collection

There are a number of issues that need to be dealt with before or during data collection in the field.  We assume that the user has calibrated the equipment and decided on a deployment strategy.  Depending on the acoustic unit used, there is also a number of collections settings that need to be specified.  Some of these are not critical as they can be changed during data processing.  But some cannot be changed later and will determine the vertical resolution and noise levels (pulse duration, power settings), and the smallest organism that can later be analyzed (e.g. collection thresholds).  In addition, it is always important to document all information as well as unusual observations during the survey.  Weather and moon light should be documented as well. 



Data management

Collection settings

  • Pulse duration
  • Ping interval
  • Raw data depth
  • File size
  • Transducer depth
  • Collection thresholds
  • Bottom backstep
  • Single fish recognition
  • GPS

    System settings

  • Transducer gain
  • Sa correction
  • Equivalent beam angle and width
  • Output power
  • Environmental settings

  • Sound speed (c)
  • Absorption (alpha)
  • Correcting incorrect settings