South Africa faces challenges in balancing economic activity derived from the shipping industry with marine environmental protection.

One of the most prominent maritime trade routes is located around the Cape of Good Hope in South Africa. As a result of escalating conflict in the Middle East since 2016, trade routes have been redirected away from the Suez Canal towards the Cape, resulting in increased vessel traffic. This has provided South Africa with expanded economic opportunities such as ship-to-ship (STS) bunkering (the process of transferring fuel from one ship to another while at sea or anchored), dry dock facilities, and resupplying vessels and their crews with essentials. However, the increase in maritime activity has also raised concerns about environmental impacts, including oil spills, underwater noise pollution, disturbance to marine habitats and the introduction of invasive species.

Oil spills are among the most visible environmental impacts of maritime shipping, with the MV Treasure spill in 2000 being one of the most significant incidents in South Africa. The vessel sank 9.7 km off the coast near Dassen and Robben Islands, which were home to the country’s largest African penguin breeding colonies at the time. The spill released about 1 300 tons of bunker fuel into the ocean, affecting nearly 40 000 penguins and several other marine species. Since this event, oil spill response procedures have been strengthened, with the Southern African Foundation for the Conservation of Coastal Birds (SANCCOB) playing a leading role in wildlife rehabilitation efforts. Both SANCCOB and BirdLife South Africa have since raised concerns about the risks associated with STS bunkering operations, citing the potential for future spills and calling for stricter regulations.

In Algoa Bay, STS bunkering began in 2016, and involved an estimated 3 000 vessels that were transiting the South African coastline annually. The business expanded rapidly, but was shut down in 2023 by the South African Revenue Service over tax irregularities. During this period of bunkering suspension, the African penguin population at St Croix Island in the Caribbean increased from 700 breeding pairs in 2023 to 1 300 in 2024. Bunkering resumed in February this year under new proposed regulations by the Department of Forestry, Fisheries and the Environment, which limit the number of permitted operators and introduce environmental safeguards.

Oil pollution is compounded by airborne emissions from vessel engines, which release sulphur oxides, nitrogen oxides and particulate matter. These pollutants contribute to ocean acidification and degrade coastal air quality, affecting both human and marine life. South African regulations align with the International Maritime Organisation’s (IMO) MARPOL Annex VI standards, which cap sulphur content in marine fuels and promote emission control areas, although enforcement capacity remains a challenge.

Noise and light pollution from ships also have an impact on marine fauna. Marine mammals and seabirds rely on acoustic and visual cues for navigation, foraging and mating. Excessive engine and sonar noise interferes with echolocation in whales and dolphins, while artificial lighting affects seabird breeding behaviour. A recent study linked increased vessel noise from STS bunkering in Algoa Bay to declining penguin populations. To curb underwater noise, the IMO in collaboration with the United Nations Development Programme and the Global Environment Facility, launched a project to investigate the impacts of underwater noise on marine life, with South Africa selected as one of six pilot countries. South Africa is also a signatory to the Convention on the Conservation of Migratory Species, which has developed guidelines to address both light and acoustic pollution.

Invasive species can be introduced via ballast water discharge and hull fouling (the accumulation of marine organisms on the hull of a ship). With 80% of international trade being shipborne, vessels inadvertently transport thousands of non-native organisms. Invasive species such as the Mediterranean mussel (Mytilus galloprovincialis) outcompete native shellfish and alter food webs in kelp forest ecosystems. Ports like Cape Town and Simon’s Town are hotspots for such invasions due to high ship traffic and suitable conditions for colonisation. South Africa enforces ballast water control through its Ballast Water Management Bill and is a party to the IMO Ballast Water Management Convention, which sets global standards for ballast treatment.

Beyond biological and chemical threats, marine debris and cargo spills also harm biodiversity. For example, nurdle (plastic pellet) spills have polluted Eastern Cape beaches, affecting turtles, seabirds and fish through ingestion and entanglement. These incidents highlight gaps in cargo handling and emergency response systems. South Africa’s National Environmental Management Act (1998) mandates that polluters contain and minimise the environmental effects of such incidents.

Vessel collisions with marine fauna, particularly large whales and sharks, pose another concern, especially along high-traffic routes near critical habitats. Collisions can cause serious injury or death to marine megafauna, with documented cases off Cape Town and Algoa Bay. Mitigation strategies such as speed restrictions, real-time tracking of marine animals and vessel re-routing during migration seasons need to be further explored.

South Africa has the well-developed Marine Spatial Planning framework and has designated marine-protected areas that cover about 5.4% of its Exclusive Economic Zone. Despite these efforts, challenges remain in enforcement, interagency coordination and ensuring that conservation priorities are not undermined by industrial or commercial interests.

Maritime shipping underpins South Africa’s economic and geopolitical importance, but this growth must be balanced with efforts to prevent ecological degradation. A sustainable future lies in integrated planning, regulatory reform and inclusive governance. With continued investment and cooperation, South Africa can protect its marine biodiversity while maintaining its role as a vital player in global maritime trade.