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Home » Research Projects » Regionally important developmental foraging grounds for green turtles and hawksbills in the Southwest Indian Ocean (2020 – 2023)

Regionally important developmental foraging grounds for green turtles and hawksbills in the Southwest Indian Ocean (2020 – 2023)

    This collaborative research initiative, led by Nelson Mandela University with support from Sharklife Conservation Group and Ezemvelo KZN Wildlife, investigated the in-water ecology of sea turtles along South Africa’s east coast, including the iSimangaliso Marine Protected Area. The project addressed knowledge gaps in relative abundance, demographics, distribution, residency and habitat use of non-nesting sea turtles.

    Principal Investigator: Natalie dos Santos (Nelson Mandela University)

    Co-Workers: Grant Smith, Ronel Nel, Santosh Bachoo

    DFFE Permit No.: Res2021/14

    Project Objectives

    The study aimed to:

    • Build a photo-ID database to assess species abundance, distribution and habitat associations.
    • Document residency and site fidelity through repeated individual sightings.
    • Collect biological data including size class, sex and behaviour.
    • Investigate movement and habitat use using complementary tracking and observational methods.

    Research Importance

    Sea turtle research in South Africa has historically focused heavily on nesting beaches, while much less is known about turtles during their in-water life stages. Understanding the relative abundance, demographics, distribution and residency of turtles on foraging reefs provides an important foundation for long-term monitoring and species-specific management.

    Methodology

    The project used a combination of non-invasive and complementary research methods:

    • Photo-ID and Underwater Visual Census (UVC): Identified individual turtles and documented relative abundance, distribution and residency.
    • Paired Laser Photogrammetry: Provided body-size measurements from underwater imagery.
    • Citizen Science and Opportunistic Sightings: Expanded the spatial coverage of verified turtle records.
    • Satellite Tagging: Complemented observational data by providing information on movement and habitat use.

    Study Area

    Fieldwork included reef sites within the iSimangaliso Marine Protected Area and Aliwal Shoal Marine Protected Area on South Africa’s east coast. Within iSimangaliso, survey effort included sites around Sodwana Bay and other monitored reef areas.

    Project Highlights

    The project established one of the first systematic in-water datasets for sea turtles on South Africa’s east coast. Long-term photo-identification revealed repeated sightings and strong site fidelity among green turtles, hawksbills and loggerheads, while complementary tagging and citizen-science records helped extend understanding of turtle distribution and habitat use.

    Published Research

    The project contributed to the peer-reviewed publication:

    dos Santos, N.A. et al. (2026). Regionally important developmental foraging grounds for green turtles and hawksbills in the Southwest Indian Ocean. Marine Biology 173, 79.

    Collaborative Efforts

    This project brought together Nelson Mandela University, Sharklife Conservation Group and Ezemvelo KZN Wildlife, with research conducted under the relevant DFFE and iSimangaliso approvals. Sharklife contributed local field capacity and in-water survey support to the project.