• Impact story
  • 07 June 2021

Impact expedition

Africa’s Greatest Marine Migration

How participation in this expedition will make a difference:

“In the end, we will conserve only what we love; we will love only what we understand and we will understand only what we are taught.”
~ Baba Dioum

Joining this expedition will immerse travellers in the wonder of this annual event and give a first-hand understanding of the sheer scale of the migration and the number of species that come together to breed and feed.

The knowledge gained about the vast distances that many of these species travel to gather in this incredible spectacle will foster an appreciation for the large-scale connectivity within and between ocean systems, and the critical importance of conservation collaboration across boundaries to ensure their survival.

Ecotourism is a powerful vehicle for mobilising change – the more awareness that can be generated around the importance of conserving this globally-important migration, the better the odds of preserving it from fishing exploitation for generations to come.

  • 07 - 17 JUNE 2022

Africa’s Greatest Marine Migration Expedition

An Oceans Without Borders Impact Journey

South Africa: Wild Coast | Phinda Private Game Reserve | Sodwana Bay

What is the importance of this great African marine migration to marine conservation?

Oceans Without Borders (OWB) is committed to improving our understanding of marine ecosystems in eastern Africa and the Western Indian Ocean to inform global marine conservation practice.

These are each major research themes common to all our OWB sites.

Extending our potential for impact to Africa’s Sardine Run is a natural and fitting extension of our work because it:

1.Illustrates the importance of connectivity between sites up and down the coast

2.Emphasises importance of apex predators to marine ecosystems

3.Highlights the ecological and conservation significance of large aggregations of marine species in one place at one time


” Oceans truly have no borders. They are the ultimate commons, connected by the salty waters that flow around the globe – a fragile blue expanse that connects us all, and on which we are all intimately dependent.”

~ Dr Tessa Hempson

The fact that all ocean ecosystems are literally connected means that effective marine conservation demands meaningful collaboration across boundaries. The sardine run is a spectacular illustration of this fact. This large scale annual migration draws animals from multiple oceans to a single location for a brief window of time, connecting populations of marine species across thousands of kilometres.

Humpback whales, for example, travel from the depths of the Southern Ocean timing their 8 000 km round- trip annual migration to be along the southern African coastline for this great event.

Apex Predators

What are Apex predators and why are they important?

Apex predators sit at the top of the food chain and generally have no natural predators. They play critical roles in maintaining healthy ecosystems as they have significant impacts on the population dynamics of prey species as well as other predators. When apex predators, such as sharks or lions disappear, ecosystems start to unravel as repercussions are felt all the way through the food chain.

Apex Predators and the Sardine Run

South Africa’s annual great marine migration draws large numbers of apex predators like sharks, dolphins and giant trevally that come to feast on the abundance of food available during the sardine run. These predators can travel immense distances to reach this great gathering, often crossing political boundaries and moving between areas of different zoning and conservation status, making them vulnerable to fishing as they travel through unprotected waters.

To effectively conserve these species, it is essential that we work together across boundaries. Apex predator conservation is a high priority for Oceans Without Borders – working with partners throughout the Western Indian Ocean, and using telemetry techniques to track these animals to improve our understanding of their movements and their key habitats. This information supports effective conservation by allowing limited conservation resources to be focused on protecting critical habitats.

Aggregation sites – the Great Gathering

What are aggregation sites and why are they important?

An ‘aggregation site’ is a place in both time and space where many individuals of a species or many different species come together. Animals often gather together to breed, ensuring that there is regular mixing of genes between populations to ensure that strong genetic diversity maximises their chance of survival. Species also often gather to feed, taking advantage of seasonal opportunities to build up their bodies’ reserves.

Like the wildebeest of the Serengeti follow the seasonal grasses during their annual great migration, so too sharks, whales, dolphins and seabirds gather in a feeding frenzy that tracks the massive shoals of sardines that gather annually to spawn on the Agulhas Bank and move up the east coast of South Africa, creating an abundance of food for a short few weeks every year.

Why are aggregation sites vulnerable to threats?

These great gatherings of aggregations are often critical events for the survival of species, ensuring the maintenance of high genetic diversity or building valuable food reserves to sustain populations through periods of relative scarcity.

But, when animals gather in such great numbers, they are also exceptionally vulnerable to being exploited. These aggregations become much easier to locate and target by fishing fleets, and with fish and predators drawn from many thousands of kilometres away, the populations of a multitude of widely dispersed marine ecosystems are potentially at risk.

Oceans truly have no borders – it is essential that we work together, transcending boundaries, sectors, classes and cultures to ensure the survival of our marine ecosystems, and in so doing, secure our own.