Experts have warned of a potential decline in South Africa’s famed sardine migration, considered the largest animal migration globally in terms of biomass, due to warming ocean waters caused by the climate crisis.
Billions of South African sardines undertake the one-way, 1,500-kilometre (932-mile) journey from temperate regions to the Indian Ocean, a migration known also as the “KwaZulu-Natal Sardine Run.”
According to a research article, titled “The sardine run in southeastern Africa is a mass migration into an ecological trap,” this migration along the Agulhas Current, one of the fastest currents in the oceans, also involves various predatory birds and other marine life.
The sardines involved in the migration also serve as a significant source of commercial income for the local population.
'Mystery'
In an interview with Anadolu, Lorien Pichegru, a lectur at Nelson Mandela University's Coastal and Marine Research Institute, said that this migration remains a mystery in many ways.
Pichegru described the Sardine Run as the largest biomass migration on the planet, noting its importance for many predators, particularly seabirds.
She noted that sardines do not like warm waters, and ongoing research is examining the impact of the climate crisis on these fish.
“We can say that sardines in Africa have decreased under the pressure of climate change and overfishing,” Pichegru said.
Temperature of seawater
“Sardines have an average lifespan of 2-3 years. So, in fact, the continuation of the sardines' existence depends on the survival of their eggs and larvae, and this is directly affected by the temperature of the seawater.”
“If the temperature is high, it becomes difficult for the larvae to grow into adults and spawn again. So, climate change definitely reduces the number of sardines.
“Under these conditions, it is likely that the sardine run may stop in the coming years. If this happens, many animals will migrate. Among them, sharks can be highlighted. At the same time, the future of Cape Gannet birds, which are already endangered, will be even more at risk. Additionally, fishermen in the region who rely on these fish for their income will also be affected. This actually means that the entire food chain will be impacted,” she added.
Pichegru also expressed concern over the impact of ongoing oil and gas exploration in the region, adding excavation work on the seabed creates significant noise pollution, which affects marine life.
Importance of biodiversity
She also warned that the Agulhas Current, one of the fastest in the world, could spread the effects of a potential oil spill over a wide area.
The 1 Ocean Foundation, established under the French National Center for Scientific Research (CNRS), is documenting the Sardine Run with scientists, artists, and activists as part of a project supported by UNESCO.
Underwater photographer Alexis Rosenfeld, a founder of the foundation, said the project, titled “The Great Migration of Life,” aims to highlight the importance of biodiversity.
Rosenfeld explained that the primary motivation for starting the project was the natural gas and oil exploration work initiated off the coast of South Africa.
Ocean currents
Concerned about these activities, they chose to highlight the potential costs through their film project rather than opposing the exploration directly.
Rosenfeld also mentioned that another factor in starting the project was climate change, saying: "Climate change has a significant impact on ocean currents, and this greatly affects migrations as well.”
Emphasising that billions of animals are involved in the migration, Rosenfeld said: "Sometimes you can't even see ahead because your view is filled with animals. There can be millions of sardines, over 50 swimming birds, and 20-30 dolphins around you. When that happens, you can forget where you are and what you're doing."
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