The long term goal of the project is to establish SRMR as a prime site for shark research and to produce scientific data that will help towards the conservation of the shark species that regularly visit THE SHARK DIVE at Shark Reef. More specifically, the Bull Shark Tagging Programme aims to better understand bull shark behaviour and ecology. It uses the full spectrum of telemetry techniques, ranging from direct observation of sharks in their natural habitat to state-of-the-art satellite telemetry.
Bull sharks can be encountered in great numbers at THE SHARK DIVE in SRMR from January until October. This is when individual sharks can be directly observed and counted to, for example, estimate the population size. During the months of November and December, very few bull sharks are seen in SRMR. Year after year they move away from SRMR during these two months to either give birth or to mate. This is known because many females are seen with fresh mating scars when they return to the site in January. Furthermore, pregnant females that left at the end of the year return non-pregnant the next year. A first and obvious question has been “where do the bull sharks go when they leave SRMR?”. A tool to address this question are pop-up satellite archival tags. To date, a total of 14 bull sharks have been tagged with pop-up tags in Fiji. A preliminary analysis of the data collected so far tells us that the bull sharks move up and down the coast, but do not leave the Viti Levu coast on large-scale. We have learned alot about at what depth and temperature they spend most of their time, but little about where exactly they go when they leave SRMR.
As a consequence, we started to also tag the bull sharks with acoustic tags. These small tags are either externally attached or fed to the sharks. A tagged shark will be picked up by so-called listening stations (acoustic receivers) that are placed on Shark Reef and neighbouring reefs. Such a receiver array provides us with presence-absence data of individual sharks, from which, together with the visual census data, inferences about site occupancy and small-scale movement patterns can be made.