FACES OF NEED – TRACKING THE GREAT WHITE

Background

Great White sharks have been IUCN red listed since 1996, and Cites appendix II since 2004. They have been fully protected in SA since 1991.

Gansbaai has been established as an extremely important hotspot for Great White sharks and food is believed to be the main attraction to the area. In winter months (May - September), Geyser Rock, adjacent to Dyer Island, provides a banquet of juvenile Cape fur seals(Arctocephalus pusilus pusilus) born each year. Various fish species such as Geelbek, Snoek and Yellowtail are available in seasonal abundance, along with smaller shark species such as soupfin shark (also known as vaalhaai), upon which the Great White Shark feeds.

Up until now, our Marine Biologist, Alison Towner, has been working on building a shark identification data base. Just as human beings have a unique finger print, Great White Sharks can be identified by their dorsal fins. We can use two methods of photo identification to identify individual sharks from one another.

Dorsal Fin identification: Using the trailing edge of the dorsal fin we can distinguish specific notch marking sequences. These are individual to sharks and can now be recognised accurately by using the latest computer program technology.

Sub-surface identification: Under water film footage and photography can enable us to identify great white sharks even more accurately by matching specific pigmentation markings on three marked areas of each shark by their gills pelvic fins and tails .

The problem

But we remain uncertain of the reasons why we see sharks patrolling the surf zone of the swimming beaches during the summer months. No one has been able to explain the incentive behind this habitat use, whether it is breeding or feeding. There are numerous interactions between White sharks and other marine animals such as dolphins, whales and seals - a unique situation rarely encountered anywhere else in the world.

The solution

The Dyer Island Conservation Trust together with Marine Dynamics, have funded a custom designed research vessel called Lwazi (“Knowledge” in Xhosa) and developed a project where we will acoustically track sharks in our area during the summer months to assess their behaviour.

THE WAY AHEAD

Discover and protect

Our ultimate goal is protection of the Great White shark species.

As a result of adequate tracking data over a reasonable time period and better understanding of the white sharks usage of Gansbaai's shallows, we can more effectively protect the white shark and its specific key foraging areas whilst informing and protecting beach users. Interactions between other marine life and great white sharks can be determined and communicated to scientists in various marine life fields which presents the unique opportunity to network and asses the white sharks role within the entire marine ecosystem.

How can you help?

We need your help in enabling this research project, which will be intensive—we will be following the sharks on a 24hour basis for days at a time. We expect the project duration for adequate data to be gathered will be in the region of three years (three summers).

Your donation helps sponsor tagging equipment and all logistical support surrounding this project.

‘Our sharks are in trouble and the more we know about then, the better we can protect them’