Stereo-BRUVS technology enhances marine monitoring of Aldabra reefs |14 March 2025

BRUV team on the boat during data collection (© Evanio Jean)

For the first time in the Aldabra Reef Monitoring (ARM) programme’s 12-year history, Seychelles Islands Foundation (SIF) successfully employed stereo camera systems for its baited remote underwater video system (BRUVS) programme.

This advancement was made possible due to a fruitful working relationship with the University of Seychelles (UniSey) and the South African Institute for Aquatic Biodiversity (SAIAB).

The introduction of stereo-BRUVS marks a significant leap forward in fisheries monitoring and management, not only within Seychelles’ exclusive economic zone (EEZ) but throughout the broader African region.

SIF’s ARM programme conducts BRUVS surveys across an extended range of the Aldabra Atoll every 5 years, with the first event taking place in 2015. This programme has several key objectives which include assessing differences in the management zones around the atoll, and monitoring changes within this unique and internationally leading marine protected area. The inclusion of stereo-BRUVS this year in SIF’s ARM programme allows for more detailed data collection and analysis of fish species within the World Heritage Site.

Stereo-BRUVS use two cameras mounted on either end of a frame that both focus on a bait canister which attracts various species to the camera’s location. This camera and bait system is attached to a rope that connects to a buoy on the sea surface, so that the stereo-BRUVS can easily be recovered after an hour of filming. In addition to gaining information on fish species diversity and abundance, stereo-BRUVS further enable utilisation of specialised software to measure the length of the fish captured in the videos. This information can then be used to estimate the weight of the fish, returning valuable information such as the life stage – i.e., how old the various fish are, as well as the biological mass, or biomass, at each of the sites around the atoll. Although fully annotating the video samples will take considerable time, quick scans have already revealed an abundance of sharks – including lemon sharks, nurse sharks, and grey reef sharks – as well as occasional sightings of tiger sharks, along with large groupers and other charismatic species.

The University of Seychelles, through its collaboration with SAIAB, are using stereo-BRUVS to support Seychelles NGOs, ministries and agencies with collecting valuable coastal marine ecosystem data on fish assemblages, while conducting independent projects too. Over the last 3 years, UniSey has also provided significant training on the use of stereo-BRUVS, including video analysis and fish identification workshops, in collaboration with Ocean Life Science.

Contributed