This research project focused on spotted ragged-tooth sharks (Carcharias taurus) within the iSimangaliso Marine Protected Area. The study examined seasonal aggregation patterns, individual identification, movement and environmental influences to improve understanding of how these sharks use important reef habitats during their annual reproductive migration.
Principal Investigator: Dr. Jennifer Olbers
Co-Workers: Grant Smith, Geremy Cliff, Welly Qwabe
DFFE Permit No.: Res2023-56, Res2024-59
Project Objectives
The project aimed to improve understanding of spotted ragged-tooth sharks during their seasonal reproductive migration by:
- Expanding the photo-identification database to track individually recognisable sharks through time.
- Examining seasonal aggregation patterns and movement between important reef sites.
- Investigating relationships between shark occurrence and environmental conditions.
- Assessing patterns of human activity at key aggregation sites.
- Exploring complementary non-invasive monitoring approaches, including environmental DNA (eDNA).
Key Study Areas
Research focused on a number of known and emerging aggregation sites within the iSimangaliso Marine Protected Area:
- Quarter Mile Reef: A well-established seasonal aggregation site exposed to regular diving activity.
- Seven Mile Reef: A reef where seasonal ragged-tooth shark aggregations have been recorded.
- Raggie Garden: An additional aggregation area identified for further investigation.
- Raggie Reef: An important seasonal aggregation site used for repeated long-term monitoring.
Research Importance
Spotted ragged-tooth sharks use a limited number of predictable reef sites within the iSimangaliso Marine Protected Area during an important stage of their reproductive cycle. Long-term information on individual sharks, seasonal abundance, movement and site use provides a stronger basis for understanding these aggregations and assessing how environmental conditions and human activity may influence them.
Research Methods
The project used complementary non-invasive monitoring methods:
- Photo Identification: Natural markings and distinguishing features were used to recognise individual sharks and document repeat sightings.
- Remote Underwater Video (RUV): Long-duration camera systems recorded seasonal abundance and activity at monitored aggregation sites.
- Stereo Camera Systems: Enabled non-invasive measurements of shark body length where appropriate.
- Environmental Monitoring: Environmental conditions were compared with patterns in shark occurrence and abundance.
- Environmental DNA (eDNA): Investigated as a complementary method for detecting shark presence without direct observation.
Collaboration
This project involved collaboration between Sharklife Conservation Group, WildOceans, Ezemvelo KZN Wildlife and other research and management partners. The work contributed to the long-term understanding of spotted ragged-tooth shark aggregations within the iSimangaliso Marine Protected Area and helped establish the foundation for continued monitoring.
Participation in Sharklife research projects is limited to appropriately approved research personnel. Student field-training opportunities are offered separately through Sharklife’s Student Programmes.