Baited Remote Underwater Stereo-Video systems (BRUVs) have long been used to survey benthic fish communities in marine environments. These stationary seafloor camera systems are made up of two HD cameras and a bait arm attached to a squat steel frame. At the end of the bait arm is a bait canister stuffed with minced sardines to attract fish to within the field of view of the camera system.

During deployments, footage is recorded onto internal memory cards which are subsequently brought ashore for download and analysis. Information collected using BRUVs is used to estimate relative fish abundance, species diversity and size (i.e. fish length) in sampled communities.

South Africa’s largest marine protected area 

The iSimangaliso Marine Protected Area (MPA) is one of the most pristine and intricate ecosystems in South Africa’s MPA network. It is situated off the North Coast of KwaZulu-Natal and covers a total area of 10 700 km², making it the largest of South Africa’s MPAs.

The MPA was first proclaimed in the 1970s, with a later offshore expansion in 2019. iSimangaliso, appropriately meaning miracle and wonder in isiZulu, is home to coelacanths, whale sharks, manta rays, thresher sharks as well as nesting leatherback and loggerhead turtles. Despite its importance, there are still critical knowledge gaps, and long-term monitoring of these ecosystems remains a challenge.

OCEANS ALIVE Project: Using BRUVs to address knowledge gaps

On 4 November, a collaborative team from WILDTRUST, the South African Institute for Aquatic Biodiversity (SAIAB) and SAEON left for a 17-day fieldtrip to the iSimangaliso Wetland Park in northern KwaZulu-Natal. The aims of the OCEANS ALIVE project were to fill in gaps and shed light on the fish and elasmobranch (sharks, skates and rays) communities inhabiting the nearshore and offshore reefs within the iSimangaliso MPA.

Although operations were hampered by a number of consecutive bad weather days, the team managed to deploy 35 BRUVs within restricted use zones (where pelagic fishing occurs) and sanctuary zones (fully protected) extending from Rocktail Bay to Kosi Bay between depths of 40 to 150 m.  

Who lives there? 

After a long day out in the sun, starting at the crack of dawn with deflating trailer tyres (to avoid getting stuck in the beach sand!), hooking the trailer to the resident tractor, venturing through a thick shrub path and pushing a nine-metre rubber duck into the pounding surf, the team finally settled down in the evening to review the day’s footage.

Our efforts were always rewarded with gratifying visuals of the underwater world. Key highlights were a tenacious tiger shark (Galeocerdo cuvier) stalking the bait canister, a resident blood snapper (Lutjanus sanguineus), an overzealous round ribbontail ray (Taeniura meyeni) cloaking the bait canister, and probably the most exciting of them all, a shiver of blacktip sharks (Carcharhinus limbatus).