Giant roman at Photographer's Reef

Lecture: Baited Remote Underwater Video Stations (BRUVS) in False Bay

One of the projects currently sponsored by the Save Our Seas Foundation is Baited Remote Underwater Video Stations (BRUVS) in False Bay. The project involves deploying cheap video cameras in underwater housings mounted on specially constructed tripods, with a bait container filled with 800g-1kg of sardines nearby. The camera and bait are positioned so that anything that comes to investigate the bait is captured on camera. If two cameras are used to get a stereo image, the dimensions of the fish and other marine life can be calculated. The camera films for one hour, and then is retrieved back onto the boat and deployed elsewhere.

The idea for these cameras and the initial development work took place at the Australian Institute of Marine Science, where BRUVS have been used for biodiversity surveys on the Great Barrier Reef, and have several advantages over the traditional methods used for surveying marine life. Transects swum by scuba divers are limited by diving safety margins, weather conditions, availability of divers, and the fish identification skills of the divers involved. Moreover, the bubbles released by the exhalations of the divers attracts some species and repels others. Controlled angling surveys – partnerships between specially trained fishermen and scientists – can harm species that are fished out from the deep ocean (their swim bladders expand as they are pulled up through the water column, and this necessitates treatment on the surface if the fish is to survive), are not suitable for large creatures, and can be destructive.

Tony and I attended a talk at the Save Our Seas Shark Centre in Kalk Bay by Lauren de Vos of the University of Cape Town, one of the researchers on the project. She explained that the relative cost-effectiveness of the BRUVS makes them an ideal monitoring tool for South Africa’s marine protected areas. The weight of the rig is such that it is easy to retrieve and deploy, and the cost is well within the budgetary constraints faced by the managers of our MPAs.

The data collected is visual, accessible, and can be subjected to rigorous analysis to obtain relative abundance measures for all the creatures that appear on film. It can also be archived, and sent around the world. It is also very useful for educating the public about marine conservation, and “brings our MPAs to shore” in a very real sense.

The BRUVS are being piloted in False Bay, which is an important region for several reasons. There is great diversity of habitat (several kinds of reef, covering 17% of the bay, sand, etc.), it is on the doorstep of a growing urban community, and has a long history of both consumptive and non-consumptive human activity. We know that our bay has incredible diversity of species, but it is important to monitor whether the MPAs are working, and to keep an eye on areas that are vulnerable and potentially over-exploited.

Lauren showed us some of the footage collected so far, and it was wonderful to see shysharks and catsharks nosing at the bait cannister, an octopus sailing in to take a look, sevengill cowsharks rubbing themselves against the camera housing, and a spearnose skate headbutting the rig. I hope that this tool can be well-used by those managing our marine protected areas!

There is another article about the project here with some photos of the rigs underwater. There are some videos on the project here. I recommend “Foiled by an Octopus”!

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Clare

Lapsed mathematician, creator of order, formulator of hypotheses. Lover of the ocean, being outdoors, the bush, reading, photography, travelling (especially in Africa) and road trips.

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