NOAA Protocols for Fisheries Acoustics Surveys and Related ...

An electronic ‘event log’ can be developed based on the SCS system. The event log is a data
management tool for relating echo sounder data with scientific operations. When operational,
the event log is routinely completed throughout each cruise to document chronological events of
the acoustic sampling, deployments, and other operational details that are important for data
processing and management. The event log can be used to register the start and stop of transects,
gear deployments, sites and transect series and associated data such as date-time stamps,
geographic location, EK500 vessel logs, and comments during survey operations.
Techniques
Event Log
SCS data
Error
Uncertainty in temperature and salinity affect sound speed calculations, which affect all
acoustical measurements. Temperature and salinity sensors must be calibrated to ensure high
quality oceanographic measurements.
Errors in logging and recording events will reduce the accuracy of survey estimates because
acoustical data will be improperly related to transects or deployments. While the information is
redundantly entered on a hard copy version of the event log, every effort must be insured to
accurately enter information in the electronic event log.
Considerations
Remediation
If temperature and salinity measurements are found to be in error, corrections to the
oceanographic data should be implemented and new sound speeds calculated. If a significant
change in sound speed is found, acoustical data should be reanalyzed.
If errors in the event logging software or SCS data are observed during the survey, contact
the electronics technician on board to rectify the problem.
Improvements
Acoustical data are continuous in two dimensions (vertical and along the ship track). CTD
profiles provide vertical measurements at a single point along the cruise track and surface
sensors provide one-dimensional measurements along the cruise track. Interpolation and
extrapolation of these data are necessary to match the physical environment to the acoustical
data. An improvement would be having the ability to collect two-dimensional temperature and
salinity measurements.
Data Management
Data, post-processed data, and associated meta-data should be routinely archived during the
survey. These data are downloaded to shore-based computers and permanently archived for each
survey. In addition to data, post-processing and other software should be archived.
44