Towed Video Survey - FRDC (2001/060) 'Characterising the fish habitats of the Recherche Archipelago'

Brief description

Habitat data collected by towed video surveys to validate sidescan sonar imagery of the seafloor within the Recherche region in October 2002, May 2003 and October & November 2003.

Lineage

Maintenance and Update Frequency: notPlanned

Statement: Towed video surveys were undertaken throughout the Recherche Archipelago to assist in validating sidescan sonar imagery of the seafloor. Once sidescan imagery was collected and processed, textural differences in the seafloor substrate could be identified and representative areas chosen for field validation. In the field, the boat was equipped with a computer running ArcPad navigation software, interfaced with a differential GPS. The sidescan sonar imagery for a particular area could be shown relative to the actual position of the boat. The video was deployed and towed across habitat boundaries or within representative habitat types, allowing 'functional' habitats to be recorded on video and correlated to the sidescan imagery. The towed video points were located using differential GPS. At a specified time period (eg 1 second) the position, time & depth (from single beam depth sounder) were recorded in a text file, along with a unique site identifier. This identifier is also overlayed as text on the video imagery, linking the site details to the video recorded for each site. Video imagery was classified according to the classification scheme. The substrate type, relief, dominant community and degree of cover where classified to describe the functional habitat at each site. The presence/absence of other communities (or biotic components) were also recorded, along with any comments about the site. The data for each site was entered in the text file, which was then used to generate an ArcView shapefile (video_tows.shp), representing actual video tows of varying length, classified according to functional habitat descriptions.

Notes

Credit
Fisheries Research and Development Corporation (FRDC)