SARDINE RUN: THE PHENOMENON

"I'm a local fisherman in Sezela... I come down every afternoon...I think sardine run for us is very important... it's the largest shoal in the world... it's an experience... you get hundreds and thousands of people running into the water... its an awesome experience... " Warren Meyer

Each year on the Eastern Coast of South Africa, in the winter months of June/July, the nutrient rich currents that bring colder water northwards of the Cape also bring millions of pelagic fish: the staple diet of every predator in the area.

Common dolphins mass into superpods several thousand strong, flocks of gannets gather in their hundreds, having left their colonies in the south, and sharks mass in huge numbers on the Wild Coast in anticipation of the shoals.

The sardines find their strength in numbers, yet are vulnerable to being forced upwards out of the deep, by sharks and dolphins. They form metamorphosing silver baitballs at the surface, twisting and dividing to avoid the ocean predators. 

Dolphins swoop, gannets plunge, seals glide and penguins jet through the baitballs in stunning visceral assaults on the sardines: the sharks lurk below and move in to finish them off... 

Some shoals are driven into the shallows, stranded by the beaches of Kwa Zulu Natal, where local people scoop them up in nets, buckets and skirts: this is what has become known as the sardine run.

Commercial netting operations have been built up around the annual event, with some years more successful than others: coastal businessmen employ

This is a place where man and nature are locked in a titanic struggle for survival. When all of these predators and more are hunting the same shoals, what will it take to keep our oceans alive?

A small shoal of sardines trapped in the shallows, KwaZulu Natal

SPECIES part one

"Over 10, 000 plant and animal species - almost 15% of the coastal species known worldwide - are found in South African waters, with about 12 % of these occurring nowhere else... It is estimated that 80% of the world's tanker traffic passes South Africa's coast." South African Government Information

Sardines are small silvery fishes that grow very quickly to reach a length of just under 20 centimeters. Because of their small size, they group together when threatened as a natural defense mechanism. When thousands of them group together, they form a shoal and act together as a collective, constantly swimming and rearranging themselves in dazzling patterns to disorient predators. Sardines filter the water for tiny plants and animals called phytoplankton and zooplankton as the source of their nutrition. Pretty much every predator in the area dines on Sardines, positioning them near the bottom of the food web.

Cape Gannets are large seabirds that have snow-white bodies with black tails. They also have a distinctive golden crown and nape. They grow to about 90 centimeters long and weigh about 2.6 kilograms. A gannet can travel as far as 100 kilometers over the ocean in search of food. When it sees its prey, it can dive as far as 10 meters beneath the surface. With a plummeting dive and powerful plunge, it uses its aerodynamic body to cut through the ocean at amazing speeds in search of the sardines.

Cape Fur Seals are among the largest fur seals in the world and are more closely related to sea lions—with their ability to walk on all fours, external ears, and a dense coat of fur on their underbelly—than they are to other seals. An adult male can be over 2 meters long and weigh over 200 kilograms. Despite their size, they have a natural ability to hunt, diving over 200 meters below the ocean surface, holding their breath for as long as 7.5 minutes. Sharks will eat Cape Fur Seals, especially the pups, when they have the chance.

African Penguins live in colonies on small islands along the coast. Adult males average 70 centimeters in length and 4 kilograms in weight. Their bodies are aerodynamic, helping them dive and swim very quickly in pursuit of their prey—small fish and crustaceans. That speed also helps them flee from their predators— Cape Fur Seals and sharks.

SPECIES part two

SHARKS: Copper Head Sharks are also known as Bronze Whalers. They are large sharks that can grow to 3 meters in length and weigh up to 250 kilograms. They like to eat sardines and can consume 20 in one gulp! Once mature, the only predator that a Copper Head has to fear is human. This means that Copper Head Shark is an “apex predator,” occupying a dominant position in the food web.

Blacktip Sharks are smaller than Copper Heads and Dusky Sharks but are still large and dangerous. Their skin color is dark gray-blue and their belly is white, with a thin white band along their flanks.

Dusky Sharks are also known as Black Whalers. They are quite similar to the Copper Heads, growing to about the same size and occupying the same position in the food web.

Common Dolphins are easily recognizable by their distinctive black back and a cape which forms a v-shaped saddle. They feed on small fish like Sardines and squid. The Dolphin makes a very fast clicking sound—several hundred clicks per second—to send out sound waves which bounce off of objects in its path. The Dolphin hears the “echoes” when the sound waves bounce back and processes the echoes into a three-dimensional image of the object. This special ability helps the Common Dolphin survive in the complex ocean environment.

Bottlenose Dolphins have a short rounded snout, described as bottle-shaped, and a smooth rounded head. Groups of Bottlenose Dolphins will also work together to trap shoals of fish, making it easier for all of them to eat. Sometimes, a Bottlenose will use its tailfin to “whack” a fish to stun it and make it easier to eat.

Humpback Whales stocky, humped, black bodies are covered with lumps called tubercles, which are actually hair follicles and are characteristic of the species. Adult females average 16 meters in length and 40,000 kilograms in weight. A Humpback can live for 50 years, if it succeeds in avoiding its predators. Once a Humpback reaches maturity, its only real predator is human. As filter feeders, Humpbacks use their baleen to eat only small fish, plankton, krill, and other tiny crustaceans.

FOODCHAIN

Sardines aren't at the bottom of the foodchain, but they're pretty close!

It would be better to describe the ecosystem as a food web, since nature doesn't work in qute the orderly fashion a "chain" would imply.

The main source of energy for life on our planet is sunlight. This is energy is captured through the process of photosynthesis, which, for our purposes, is handled by phytoplankton, near microscopic plant life that populates our oceans in cast quantities, harnessing the suns energy and providing the most basic food source for other oceanic life.

Which includes zooplankton, tiny, often larval, creatures that also swarm our seas, and along with phytoplankton, are subject to the ebb and flow of ocean currents, dictated largely by the flow of warm versus cold water.

Many creatures use plankton as their main food source: these are the filter feeders who simply swim through swathes of plankton with their mouths agape, seiving the foodsource from the sea water. Some filter feeders are huge: whale sharks and humpback whales for example, such is the volume of plankton in the ocean.

Sardines are, of course, filter feeders, and they will follow the plankton as the swarms are manipulated by ocean currents.

If plankton are the "producers" in the oceanic food chain, sardines are simply the first level of predation. They take three years to develop from their own larval stage into a full grown fish: rich in Omega 3 oils protein, immediately becoming a target for virtually every other predator in the ocean.

Game fish, birds, sharks, seals, dolphins, whales... all of these top tier predators pursue the sardines. Whilst some larger predators may eat other smaller predators, there is really no escape for the sardines, becoming "secondary producers" for the majority of large predators.

At the end of the day however, the larger predators die, and their bodies sink to the bottom of the sea... where they are consumed by zooplankton. This is when the food chain becomes part of something much bigger: the carbon cycle. But that's another story...

For an in depth look at oceanic food chains, vist oceanworld.tamu.edu.

WILD OCEAN: LOCATIONS

The film was shot in two distinct areas: KwaZulu Natal and the Transkei. Bordering on each other, they are very different parts of South Africa.

KwaZulu Natal's coastline, south of Durban, is is dotted with seaside towns like Margate, Scottborough and Port Edward. Towns that would not look out of place in the UK or the US.

Further inland, however, is the Zulu territory, once ruled over by the king ShakaZulu: an area rich in history and tribal culture, yet suffering economically.

The Transkei is one of several tribal lands granted independence in the early eighties, and officially became a part of South Africa only as recently as 1993. As a result is nowhere near as developed as KwaZulu Natal. It's coastline, known as the Wild Coast, is one of the most unspoilt coastal areas in the world with stunning freshwater waterfalls cascading directly into the sea.

Spectacular as the area is, the Xhosa population is close to poverty.

With no harbours, and no coastal road, the Wild Coast has had little or no development: and recently it was designated a marine reserve: a no go area for fishermen.

Just south of Port Edward lies an area known as the "red desert" which is rich in iron ore. Developers are keen to exploit this. Also, there have been proposals for a new coastal highway passing through the Transkei. Both developments could have huge economic and ecological impact: as ever, life is in the balance, and the question remains, who or what will really benefit?

 

DIVING THE RUN

The film-makers first heard of the sardine run from an article in a UK Dive magazine, called "Run, Sardine, Run"

A stunning photograph by Doug Perrine, of sharks pushing through a baitball, won the BBC WIldlife Photographer of the Year competition in 2004, and convinced the film-makers that here was a subject for the Giant screen and especially for 3D.

Diving the sardine run, however, is not for the faint hearted, or the inexperienced. This is cold water, wild seas, difficult access, and there's a lot of waiting, searching and more waiting...

Dive companies based in the area do offer trips however, and there are lots of other diving opportunities along the KwaZulu Natal coast.

We'll be adding links to dive trips for 2011 soon...

 

SARDINE RUN UPDATES

The film was scouted in 2005 and shot over two South African Winters in 2006 and 2007.

The film's conclusion touches upon two important elements; global warming and overfishing, with a plea for the establishment of more marine reserves around the world. The Wild Coast was designated a reserve shortly after the film was made.

Meanwhile, the total allowable catch designated by the South African government has been cut considerably in the years since production, a clear sign of declining fish stocks. Management of the ocean resources remains a matter of vital importance globally.

What of global warming and rising sea temperatures? Whilst some debate the issue, the majority of scientists in the field have no doubt ocean temperatures are rising and that carbon emissions continue to be the primary cause.

As the film explains, the sardines will not enter water over 19/20 degrees centigrade. So as ocean temperatures rise, the likelihood of this particular run taking place will decrease. The predators will simply have to look for the sardines in deeper water.

The real measure of a "successful" run is the number of fish taken on the beaches of KwaZulu Natal. This really shows how far north the sardines have travelled, and how far north the cold water has pushed.

2005, when the film was scouted, was something of a bumper year. 2006 and 2007, however, the waters around the KwaZulu Natal coast resolutely remained above 20 degrees. This trend continued in 2008, 2009.

In 2010, however, the temperatures dropped, and the sardines returned to KwaZulu Natal. The film-makers were in South Africa shooting Great White Shark 3D, and monitored news of netting all along the KwaZulu Natal coast.

Unfortunately, this doesn't mean the trend towards global ocean warming has stopped, it simply adds a bump in the graph: it does mean however, the run is not finished yet!

The best way to keep up to date, and find out exactly what is happening between May to August is to follow the KZN Shark Board website and hotline.