Fladen experimental fishing impact recovery data - Acoustic data

notPlanned

One hundred percent multibeam bathymetry and backscatter data were acquired in six experimental boxes and at all time points (Time 0, Time 1 and Time 2) using a Kongsberg EM2040 system operated at 300 kHz and deployed on the drop keel of the research vessel. Variations in sound velocity with water depth were determined using a CTD (Conductivity Temperature Depth) probe and applied during Multibeam data acquisition. Tidal information was gathered using a CNAV 3050 DGPS receiver. Tide height data was processed using c-Tide software and applied as a tidal correction during the processing of the bathymetry data. Survey lines were spaced at 16m across the box in an North South orientation. Two survey lines ensured 100% multibeam echosounder data coverage and overlap while a third line, in an East West orientation, was completed at each box for data quality purposes. Bathymetric data were processed for coverage and comparison using the Caris HIPS & SIPS software. Backscatter data were processed in Fledermaus geocoder tool box (FMGT) for coverage and comparison. The raw Multibeam files were processed in Caris HIPS & SIPS, which resulted in tidally corrected bathymetric soundings being produced. These soundings were hydrographically reviewed, and any erroneous soundings removed from the dataset. The time-series seabed reflectivity values (backscatter) were processed using QPS FMGT (Fledermaus GeoCoder Toolkit). This software package contains an implementation of the Geocoder algorithm which normalises and corrects the backscatter values for time varying gain, angular varying gain, and slope aspect. The resultant processed backscatter values were then analysed in ESRI ArcMap, and output imagery generated.