Baited Remote Underwater Video Systems

The basic concept of Baited Remote Underwater Video Systems is to use bait to attract fish or other animals into the field of view of cameras.

There has been a recent expansion in the application of baited video techniques to overcome the fish sampling limitations imposed by depth, fish behaviour, seafloor rugosity and the selectivity inherent in hook, trap and trawl methods. They are now proving particularly important for surveying numbers and lengths of animals in marine parks where non-destructive sampling is essential, for animals of special conservation significance, such as sharks and in rough grounds where the use of traditional fishing gears is impossible. In general terms, a bait plume is used to attract fish or other animals into the field of view of a video camera where they are identified, counted and measured. The use of a stereo system (twin camera setting) allows measuring every feature appearing in the field of view thanks to a calibration process made prior to deployment.

Each baited remote underwater video system weights about 100 kg and is equipped with:

• a twin set of HD camera in special housing able to resist the incredible pressure found at these depths,
• LED system to give light at depth,
• bait to attract fish in the field of view of the camera
• a depth and temperature sensor to record the physical parameters where the system is working.

The general benefits of the technique lie in three main areas.

1. Baited video approaches are non-extractive and do not cause major disturbance to the substrata and its epibenthos. This means they can be used in marine reserves and rugose seabed topographies, and to gather information on numbers and size of animals of special conservation significance.
2. Large, mobile animals that avoid SCUBA divers and extractive fishing gears are included in samples. All animals passing though the field of view, in response to the effect of bait or not, can be recorded. This lack of size selection, and the powerful sampling replication afforded by multiple camera units, avoids ‘false negatives’ and allows standardised sampling at any depth, time of day and seabed topography.
3. The acquisition of a permanent tape record removes the need for specialist observers to conduct all fieldwork, allows impartial, repeatable measurements, enables standardised data collection and training in association with remote taxonomists (via emailed imagery), and provides a remarkably popular format to communicate science to the public