Update on Ocearch tagging and plans for False Bay
On the 4 May the Department of Environmental Affairs (DEA) re-instated the research permits to the Ocearch team and collaborating scientists after an investigation found no link between the tagging and fatal shark attack on David Lilienfeld. Tagging commenced in Gansbaai the following Monday and within two days six great white sharks ranging in size from 3 – 4.2 meters of both sexes were captured, tagged and released successfully. The total number of satellite tagged great whites from this expedition is 34 for the South African coast. The scientific information collected so far is exciting and for the first time scientists are collecting information from the west coast and Atlantic seaboard side of South Africa where very little is known about white shark presence, new coastal aggregation sites like the Wilderness are being revealed and two sharks have spent significant time offshore in the Southern ocean.
So far only three of the 34 sharks have been tagged in False Bay. There are six satellite tags remaining from the expedition to be deployed on False Bay great whites. Research has shown that False Bay has the largest average size sharks along the South African coast and indeed the largest shark tagged on the Ocearch expedition has been a 4.6 meter female from Seal Island, False Bay. These large sharks are the ones that pose a risk to beach users and therefore the ones important to monitor over the next 5 – 10 years. The use of satellite transmitters will enable the scientists to monitor the daily movements of each study animal for a period of up to five years. These data will be used to identify areas where white sharks are vulnerable to exploitation, identification of habitats that are critical for mating, birthing, and feeding, and insight as to whether South Africa’s white shark stock can adequately be conserved locally or whether regional or international cooperation is necessary. In addition, the use of internally placed RCODE acoustic transmitters will allow monitoring of the coastal movements of animals for up to 10 years showing their seasonal use of different habitats and residency in the coastal and near-shore zones where acoustic receivers are deployed. The information collected will help enhance bather safety through identifying areas and times of high shark activity, and assist scientists in correlating environmental and biological conditions to predict high shark presence in the future.
As per the permit conditions a maximum of 25 kg of chum can be used per day (equivalent to 5 standard boxes of pilchard). The sharks will be caught and brought onto the ships specialized platform which is initially submerged, but is then lifted out of the water for a maximum duration of 12-15 minutes while the satellite and acoustic tags are attached and sampling is completed. Each shark is assessed by a vet before tagging proceeds. The shark is monitored under veterinary guidance and maintained on the platform by water over its gills. The sampling protocols for this project are based on the latest scientific knowledge and work is being done according to agreed and approved protocols based primarily on ethical considerations which have been sanctioned by the Department of Environmental Affairs as well as through collaborating institutional ethics committees. Furthermore, an independent observer from the City of Cape Town will be onboard at all times for work in False Bay.
The research can be conducted in False Bay between 14 – 31 May. Only a few days are needed to complete the tagging of six animals during this time period. The days of work are weather dependent, and so far the plan is for the research to start at Seal Island on Tuesday morning 15 May. Shark Spotters (through our website, Twitter and Facebook) will provide updates on when tagging will take place and provide an update after each day of tagging.
This research is invaluable in the objective to find a balance between water user safety and white shark conservation along the entire SA coastline and for the first time members of the public can see the near-real time tracks of the tagged sharks themselves and follow their movements. A mobile app and social network platform is being developed to allow everyone to see the latest positions of the tagged sharks. In the meantime the tracks are updated weekly on the Ocearch Facebook page: https://www.facebook.com/OCEARCH