At the tip of Africa, two oceans collide, creating one of the most productive ecosystems on the planet. Here, one of the largest shoals of fish known to man forms the basis of two food chains that split and extend for hundreds of miles. Each shoal passes its own critical point after the sardines part at Cape Agulhas.

On the west coast of Africa is Malgas Island, a traditionally energetic hub of life dominated by the presence of the supreme sardine hunter, the Cape Gannet. On the opposing coast, the shoals pass Bird Island, the eastern equivalent of Malgas.

Circumstances in the two bird colonies are very different; we see dwindling numbers of sardines on the west, while the situation on the east, on Bird Island, is the opposite.

While the Malgas Gannets battle to raise chicks amid skirmishes by Kelp gulls and hungry seals, the Bird Island gannets move to intercept huge volumes of sardines.

What transpires is one of the planet's most significant marine feeding events.

These two parallel scenarios show how one environment mutates under pressure while the other experiences a bumper season.

Will the gannets of Malgas Island adapt to their changing world?

Can the disappearing sardine stock survive, supporting the wide array of marine predators that rely heavily on it?