South Africa's Teeming Seas

The sky was white with gannets and filled with their manic chatter. Wings folded to their sides, they plummeted into the sea like feathered missiles, leaving green bubble trails in their wakes. They were hunting sardines, and the water boiled with fish. It was as if this patch of sea off the eastern coast of South Africa had been turned into a pot of bouillabaisse—and everyone was falling to the feast. Scores of circling dolphins harried the sardine shoal into an ever tightening mass. Panicked sardines threw themselves into the air and splashed back into the melee. A pale pink dorsal fin sliced through the midst. Then another. "Copper sharks!" said Mark Addison, our boat skipper. "Fantastic! Look—three, four, five of them." Tails lashing, they lunged and rolled in an orgy of feeding.

The sky was white with gannets and filled with their manic chatter. Wings folded to their sides, they plummeted into the sea like feathered missiles, leaving green bubble trails in their wakes. They were hunting sardines, and the water boiled with fish. It was as if this patch of sea off the eastern coast of South Africa had been turned into a pot of bouillabaisse—and everyone was falling to the feast. Scores of circling dolphins harried the sardine shoal into an ever tightening mass. Panicked sardines threw themselves into the air and splashed back into the melee. A pale pink dorsal fin sliced through the midst. Then another. "Copper sharks!" said Mark Addison, our boat skipper. "Fantastic! Look—three, four, five of them." Tails lashing, they lunged and rolled in an orgy of feeding.

Sardines are winter's gift to South Africa's east coast waters: an all-you-can-eat seafood buffet that attracts diners by the tens of thousands. Sharks, seals, seabirds, dolphins, and game fish converge on vast schools of Sardinops sagax, the South African pilchard, or sardine, which migrates northward along the coasts of the Eastern Cape and KwaZulu-Natal between May and August.

On shore the fever can be almost as great as in the shoals. People flock to the coast, where beach seiners haul in bulging netfuls of sardines. Sometimes nets are superfluous. Forced inshore by predators, shoals simply wash up in the surf-glittering sardine waves that dump fish knee-deep on the sand.

At Illovo Beach, 20 miles (32 kilometers) south of Durban, I watched the "rainbow nation," as post-apartheid South Africa likes to think of itself, united in harvest. An Indian woman, glamorous in her fine sari and gold jewelry, laughed as she hurried up the beach with handfuls of fish wriggling in her manicured fingers. A barrel-chested Afrikaner, tanned the color of mahogany, talked to netters as they sorted their catch into baskets and grumbled about the price. Ten rand a basket was the going rate—just under a dollar for 40 pounds (18.1 kilograms) of fish. At the water's edge, Zulu mothers gathered fish into their voluminous skirts while their children darted forward, burrowing into the folds of each incoming net to scoop out the silver slivers and stuff them into supermarket bags, jackets, shirt pockets. No one scolded. There was plenty for all.

The communities on this coast, sniffing tourist dollars in the sardine windfall, have dubbed the event "the greatest shoal on Earth." The public can phone a toll-free hotline to hear which beaches have the best sardine action, and the town of Scottburgh has started up a sardine festival, complete with karaoke, beach competitions, and cooking demonstrations using the traditional Afrikaner three-legged pot, or potjie, now jokingly referred to as the Mandela microwave.

Photographer David Doubilet, who has documented many of the planet's aquatic extravaganzas, calls the sardine run "one of the most amazing pulses of life in the world's oceans," a phenomenon every bit as dramatic as the migrations of the African savanna. In fact, the whole South Africa coast—from the coral reefs of the Indian Ocean to the kelp beds of the Atlantic—is one of the richest, most biologically diverse and most oceanographically complex marine environments on Earth.

The coastline of South Africa, stretching 1,740 miles (2,800 kilometers) From Mozambique to Namibia, is presided over by two great oceanic systems: a powerful current on one side of the continent and a strong upwelling on the other. Like potentates, they control what happens in their respective realms.

The ruler of the east is the Agulhas Current, the African equivalent of the Gulf Stream, sliding southward at up to five miles an hour (eight kilometers an hour) and shifting warm Indian Ocean water from the vicinity of Mozambique toward the southeast corner of the continent. Coral reefs are a flamboyant ecological signature of the Agulhas coast. Diving on the reefs at Sodwana Bay, near South Africa's border with Mozambique, is an experience of visual overload. There is not one surgeonfish species but 20; not one moray eel but a dozen. Corals, fishes, anemones, shrimps—everything comes in multiples. Trying to take it all in is like listening to a jazz tune with a million variations.

If luscious diversity characterizes the tropical east, then in the domain of the western potentate productivity is king. Along the Atlantic coast from the southern tip of the continent to as far north as Angola, the controlling oceanic process is the wind-driven Benguela upwelling system, which draws cool, nutrient-rich water from the seafloor to the surface. Think of it as a giant submarine pump that replenishes the fertility of inshore waters, greening them with phytoplankton and nourishing the entire food chain. The Benguela system supports the largest mainland seal colonies in the world, masses of seabirds, endemic penguins, and fisheries that provide employment for 25,000 South Africans as well as recreational angling.

Kelp, especially the giant Atlantic variety Ecklonia maxima, called sea bamboo, is the trademark of the western coast. Like its terrestrial namesake, sea bamboo grows at a prodigious rate—up to half an inch (1.3 centimeters) a day—and the fronds, eroded constantly by wave action, produce six times their own weight in detritus each year, making the kelp ecosystem one of the most productive on Earth. Finning through jungles of it, thrusting aside the stipes as thick and smooth as baseball bats, which reach 30 feet (9.1 meters) and more toward the surface, makes you feel like an underwater Livingstone or Stanley, with discoveries waiting at every turn.

Under a swaying kelp canopy on a rocky shore near Cape Town, I found marine snails as big as grapefruit and massive limpet-like chitons whose chunky overlapping shell plates gave them the appearance of having just crawled out of the age of dinosaurs. A rock slab was completely covered with Cape urchins—orange, mauve, and tomato-colored, each with a barricade of fine spines. Baby abalones, or perlemoen (after the Dutch word for mother-of-pearl), hide beneath them to escape the attention of predators. I lifted up a couple of urchins, and sure enough, three or four fingernail-size perlemoen scooted across the rock to find another shelter.

Among the gray hottentot fish, scarlet romans, and other reef denizens gliding between the kelp stipes were shysharks, which curl into a ring when threatened, cover their eyes with their tails, and drift about like a cartilaginous quoit until the danger is past. They sleep stacked one on top of the other under ledges. I found one of their pale yellow egg cases—a "mermaid's purse"—tied to a kelp frond; a bauble from the Benguela crown.

The two oceanic titans, flexing their muscles on either side of the continent, indulge in a bit of arm wrestling along its blunt southern flank. Satellite images of sea surface temperatures show the Agulhas Current as a yellow tongue of fire licking at the green reservoir of cool southern waters and flinging warm eddies westward into the Benguela system. It is the interaction between warm and cold, east and west, that makes the South Africa coast unique. Although there are three other major upwellings in the world—off the coasts of California, Peru, and northwest Africa—only in South Africa is the cold, productive west coast upwelling influenced by a warm, fast-flowing east coast current.

The sardine run is an indirect result of that interplay. By rights sardines shouldn't be on the eastern coast at all. They are cold-water fish, and their stronghold is the southern and western coasts, where the Benguela holds sway. There they are harvested in their billions by purse seiners and turned into fish meal or cooked, sauced, tinned, and sold under a dozen different brands (one describes the product as "brainpower food"). Together with their close relatives the anchovies and herrings, sardines make up about a quarter of the world's fish catch.

For most of the year inshore water temperatures on the east coast are warmer than 68 degrees Fahrenheit (20 degrees Celsius) and outside the sardines' comfort zone. But in winter a combination of cooling land breezes and a mild upwelling of Agulhas Current waters onto the continental shelf creates a narrow, cool-water corridor that sardines can exploit.

It is as if the eastern potentate had turned his back for a moment. The sardines, seizing their opportunity, move northward, find the corridor, and stream up the coast like lemmings. Once they reach Durban, those that haven't been caught, eaten, or beached spread out onto the continental shelf to feed and spawn. As the surface waters are warmed by the growing heat of the spring sun, the sardines descend to cooler depths, but eventually rising temperatures drive them back south to rejoin the parent population off the Eastern Cape.

Not many of South Africa's sardines choose the travel option—perhaps 30,000 tons (27,215 metric tons) of fish in all—but enough do for the KwaZulu-Natal sardine run to be considered one of the marine wonders of the world.

Doubilet and I timed our arrival to coincide with the front-runners of the sardine migration: pilot shoals of perhaps half a million fish that start to appear about the first week of June. The main shoals come some weeks later. These mother ships of the sardine fleet can cover several square miles and contain hundreds of millions of fish.

Rather than wait for the shoals to reach us in Durban, we decided to head south with Mark Addison, a multitalented marine guide who specializes in the sardine run, to meet the fish on their way north. We based ourselves at Mkambati Nature Reserve, just south of the KwaZulu-Natal border with the Eastern Cape.

Mkambati is one of the few places along this cliffbound stretch of coast where a boat can be launched—and then only if the sea permits. Not without reason is this called the Wild Coast. Tankers break their backs out here when storm waves from the Southern Ocean, forced upward into steep peaks by the south-streaming Agulhas Current, superimpose to form ship-swallowing swells 60 feet (18.3 meters) high. We never tackled seas greater than a tenth that size, but the daily rodeo ride out through the breakers in Addison's 22-foot (6.7-meter) inflatable—and later, the hair-raising return trip, hurtling right up onto the beach on the crest of a curling wave—left us in no doubt about the power of the Indian Ocean.

In our search for shoals, it was the gannets we saw first in the distance, looking like swirling flecks of ash. Addison—cap jammed down on his shaven head—would open the throttle and race for the spot. If lucky, we would arrive to find the glorious chaos of a fully developed bait ball. These aggregations of ultimate frenzy are created when common dolphins ("common" both in name and number) work together to shear off a section of a shoal, corral it into a scrum the size of a tennis court, and force it to the surface. Only then do other predators appear, making the whole thing, as Addison says, "go ballistic."

The result is an eruption of fin and flesh. Dolphins squeal like sirens as they make strafing runs at the edges. Eight-foot (2.4-meter) copper sharks thresh their way through the shoal, biting and gulping. Cape fur seals, elastic underwater acrobats, corkscrew up through the middle then flip backward, snapping up fish on the way over. And all the while gannets rain from the sky, so fast and so many that it looks as if they are being sucked into the ocean by a vacuum cleaner.

During our weeks at Mkambati we dived on dozens of shoals, and every one was different. Some shimmered like blue carpets that suddenly turned silver as the fish caught the sun on their sides. Some were so solid and dense right down to the seafloor that swimming underneath them was like crawling under a mattress—and just as dark. Others were on the move, specks of light streaming ceaselessly toward us as mesmerizing as a computer screen saver. Sinking down into one shoal, I found myself in the hole of a sardine doughnut, being watched by innumerable unblinking yellow-rimmed eyes.

We found schools with just a few seals in attendance, not feeding so much as playing with the shoal—treating it as a living beach ball. Watching sardines part and re-form around a seal is like watching some super—organism reshaping itself with effortless mathematical precision. Occasionally our inflatable brought us upon the scene of a bait ball that had dissipated—or been consumed—nothing remaining but a few scales and a lingering smell of sardine oil.

The presence of sardines must be a powerful drawcard for predators, for they come a long way to dine at the potluck. The nearest seal and gannet colonies are at Port Elizabeth, 300 miles (482.8 kilometers) south of Mkambati. Both species rest on the sea surface between feeding binges—gannets in large flocks, seals in rafts of a dozen or so, lying on their sides with a flipper raised in the air for cooling. On calm days we spotted dozens of seal rafts, each animal giving its one-flipper salute as we passed.

Dolphins—bottlenose and common—are residents of this coast, but they are never here in such large numbers as they are during the sardine season. On one occasion Addison took Doubilet and me 10 miles (16.1 kilometers) offshore to dive with a thousand-strong herd of common dolphins traveling northward against the current. Addison dropped us in the water a mile (1.6 kilometers) ahead of the herd and retreated. We were in the heart of Agulhas country: over one shoulder the land a distant smudge, over the other a tanker crawling along the horizon toward the Cape, ahead a phalanx of dolphins advancing.

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What is the sound of a thousand dolphins? It is like river rapids, or a sudden cloudburst. Close to the herd you can make out the individual pffffts of blowholes opening, stale air being expelled and fresh breaths sucked in. And, faintly through the puffs and splashes, the high-pitched squeaks and whistles of dolphin communication. Underwater, where those unearthly sounds are heard at full volume, it's like being serenaded by a chorus of dentist's drills.

The dolphins came on in a rush, wavefuls of them leaping out of the face of the ocean swells as if jet-propelled, the sunlight gleaming off their cornmeal-colored flanks. Streamlined and athletic, Olympians of their kind, they had a focused intensity about them. "Places to be, things to do," they seemed to be saying as they sped past.

Sharks, those legendary "swimming noses," were never far from the sardine supply. They had a knack for materializing out of seemingly empty ocean. You would think you were alone—and then there would be a shark only a few feet away.

The main species associated with the sardine run is the copper shark (also known as the bronze whaler), but spotted ragged-tooth sharks also take the occasional sardine meal. Like other migrants along this coast, ragged tooths—known elsewhere in the world as gray nurse or sand tiger sharks—move north during sardine season from the cool southern waters to the tropics to breed.

After leaving Mkambati, I followed the "raggies" to Aliwal Shoal, 30 miles (48.3 kilometers) south of Durban and three miles (4.8 kilometers) offshore. Due to the Agulhas Current's southward shift of tropical water, Aliwal has some of the southernmost hard coral communities in the world. It is also thought to be a ragged-tooth mating area. During the day the sharks can be found resting, almost immobile, in the reef's many caverns and amphitheaters. In one, called the Cathedral, I found several floating like gray ghosts. With the merest twitch of their tail fins they adjusted their position, slowly rising and falling as if in a trance, while around the craggy walls shoals of sea goldies, a vivid orange tropical fish, swirled like autumn leaves. It is a strange thing to see a motionless shark. Many sharks, lacking the bellows-action gill covers of bony fishes, must keep moving to oxygenate their gills. Ragged-tooth sharks are an exception. They also possess the ability—unique among sharks—of gulping air from the surface to achieve neutral buoyancy.

The sheen of their olive skin, dappled with dark brown blotches, the humped back and beveled snout, the small, pale eyes with a black dot at the center—a resting raggie gives you plenty of time to linger over these details, and to focus on the feature that gives the shark its name: its orthodontist's nightmare of a mouth. Most sharks keep their hardware concealed behind their fixed crescent frowns. Raggies look as if they're holding a mouthful of nails.

Unlike the great white shark's triangular cutting teeth, sharp as a set of chef's knives, the front teeth of a ragged-tooth shark are slender and pointed, for grabbing, while the back teeth have rasplike surfaces for gripping and crushing. At the front of the jaw each tooth has as many as four replacements, opening out like blades of a pocketknife. Baby ragged-tooth sharks put their teeth to swift and deadly use: In one of the few instances of intrauterine cannibalism known to science, the dominant embryo within each of the raggie female's two uteri eats its siblings before it hatches as a 3-foot-long (0.9-meters-long) superpup.

I returned to Aliwal at dusk with Mark Addison to see ragged teeth in action. Raggies become more active in the evening, and Addison has found that they will readily accept a free handout from him. By observing the sharks at close quarters, he hopes to better understand their feeding behavior—though some divers worry that this sort of activity may cause sharks to associate humans with food, a potentially fatal combination.

"Now remember, big guy," Addison warned, "their jaws lock when they bite. If you get bitten, push the snout up, and the shark will let go." Sure it will, I thought, picturing myself swimming around with a 500-pound (227-kilogram) shark clamped to my arm.

We dropped beneath choppy seas and a strong current to a sandy area that was about to become "Raggies Restaurant." Addison stuffed two plastic drums of bonito into a crevice in the reef, then took out several fish and placed them under rocks. Soon there were a dozen sharks circling round. Often they would swim right past a fish and apparently not notice it. Sometimes they would detect the prey but seize the rock instead. Such mistakes usually cost them a tooth or two, left behind on the sand like chips of white china.

Addison started hand-feeding the sharks and passed me a bonito so I could do the same. Two or three sharks swam by, not seeming to notice my offering, so I thrust the fish more pointedly under the nose of the next in line, and the shark mouthed it delicately. I could feel the teeth puncture and compress the fish as it was pulled away from my hand. Then the jaws opened, and the fish was gone.

It all seemed very genteel. But ragged-tooth sharks are by no means so mild mannered in all situations. The International Shark Attack File ranks the species fourth in "unprovoked attacks" on humans, behind the Zambezi, tiger, and great white. Addison believes ragged-tooth behavior is linked to water temperature. "In the Cape, which is 15 to 20 degrees colder than Aliwal, raggies are much more aggressive," he says. "The spear fishermen there talk of them with total respect and are very wary, whereas here we can spear fish in the midst of a bunch of raggies and not be hassled by them. But if the water temperature drops a few degrees, the gentle giant awakes. Their normally docile nature changes, and they become fish stealers."

It was to the colder, sharkier waters of Walker Bay, 60 miles (96.6 kilometers) southeast of Cape Town, that Doubilet was headed to lock lenses with an old quarry, the great white. I went farther west, to the heart of the Benguela kingdom, to see the kelp beds and penguin colonies of Cape Town. Some Capetonians believe that the Atlantic and Indian Oceans collide right off the end of their famous peninsula. Indeed, I read in a Cape Town newspaper that a local diver reckoned he had pinpointed the exact spot. It's wishful thinking, and yet standing on the precipice at the tip of the Cape of Good Hope, it is tantalizing to imagine that out there somewhere two oceans are locked in combat.

It took several days before I could get out on the water. The Benguela coast is as renowned for its meteorological violence as for its nutritional productivity, and the Cape Peninsula, jutting into the Atlantic like a claw, catches the worst of the weather. Sir Francis Drake is said to have called the Cape of Good Hope "the fairest Cape…in the whole circumference of the earth" but other sailors knew it as Cabo Tormentoso, the Cape of Storms, destroyer of ships.

A dense sea fog was on the water the morning Eric Simpson—my dive partner—and I finally made our dash for the Cape. We headed for a reef called Bellows. Its name, and that of its neighbor, Anvil, give fair warning that a boat can be hammered out here in this smithy of the seas.

The swell was viscous and the color of lead as we passed Buffels Bay and neared Cape Point. Suddenly, on our port side, fishing boats appeared out of the mist. "Snoek," said Simpson, and his eyes lit up. When not working as a cameraman and diver, he fishes commercially for snoek, the local name for a large mackerel. Simpson called out a greeting to a couple of the skippers. Most of the boats were fiberglass runabouts—ski boats, they're called here. Each had half a dozen crew working two lines apiece and pulling in flapping, four-foot snoek one after the other. They would be taking home a big haul today, 40 or 50 a man. "You can't know how this is hurting my fisherman's heart," Simpson said enviously as we motored away.

The lighthouse on Cape Point was starting to show through the murk as we anchored. We dropped over the side and finned down the anchor warp, bottoming out at 100 feet (30.5 meters). There, spilling like gold from a treasure chest, was the densest concentration of lobsters I'd ever seen. Every crevice bristled with them. Those that had no cleft to call their own were out in the open, skittering about on tiptoe or shooting away with a sudden snap of their tails. One adventurous crustacean had climbed up a sea fan and was clinging to it like a mountaineer pondering his next move. I plunged into a thicket of the creatures just for the marvel of seeing the pell-mell scurry and scatter of a thousand lobster limbs.

Evidence of Benguelan abundance was all around. The walls of the reef were packed with encrusting life as tightly as supermarket shelves. Red bait—sea squirts the size of a rugby ball with sides as tough as old leather—were jammed together with anemones and feather stars. Tree-shaped growths of a coldwater species called noble coral, with bubble gum pink branches and white tips, looked like something that should be shrink-wrapped and sold as confectionery.

As I swam along a wall, engrossed with finger sponges and candelabra fans and daisy anemones in all their paint box glory, Simpson tapped me on the arm, and I looked up to see a copper shark cruising by. With the softly diffused sunlight shining on the splendid arch of its back, it seemed a princely ambassador for the opulent Benguela realm.

A more endearing representative is the stocky, pink-eyebrowed African penguin. Cool, rich waters make it possible for penguins—birds we normally associate with icebergs—to enjoy a breeding range that includes islands off the coast of the Namib Desert.

One morning when the "Cape doctor"—Cape Town's invigorating southeasterly wind—had yet to begin his rounds, I slid a kayak into the harbor at Simon's Town to go penguin watching. I paddled out into False Bay—past the stone walls of the old British naval dock, where fur seals rolled and splashed; past a submarine returning from an exercise; past an offshore nubbin of rock packed with roosting cormorants.

A mile (1.6 kilometers) or so up the coast, at a beach called Boulders, I parked a hundred yards (91.4 meters) offshore among the floating mop tops of sea bamboo and watched penguins from one of South Africa's few mainland breeding colonies commute to their feeding grounds. Groups of 20 or 30 would swim tentatively toward an opening in the kelp, bobbing and shaking their heads and looking around like nervous meerkats, then make a mad dash through the channel. Their anxiety is not surprising, for seals and sharks feed along these shores, and both have an appetite for penguin.

As the penguins sped away, one dived right under my kayak, flippers outstretched, a black dart against the white sand. How perfectly it fitted its Latin name: little plunging wedge. I wished it well as it ran the predator gauntlet, for Africa's only endemic penguin has not had a happy history. Since the 1600s African penguins (also called jackass penguins on account of the donkeylike braying of the male) have been harvested for food, rendered for fat, burned as fuel in ships' boilers, and used as bait for lobster pots.

And that's only the adults. In just three decades, between 1900 and 1930, 13 million eggs were collected, most from Dassen Island 40 miles (64.4 kilometers) northwest of Cape Town, one of the main breeding colonies. Even the penguins' guano was exploited—scraped up and sold for fertilizer. That process destroyed much of the breeding habitat because the birds build their burrows in the soft deposits.

Although the harvesting and scraping has ceased, the penguins remain vulnerable. In the winter of 2000, spilled fuel oil from the bulk carrier Treasure threatened 70,000 penguins on Dassen and Robben Islands—40 percent of the total penguin population. Realizing they would be unable to clean such a large number of oiled birds, wildlife authorities decided to buy time by trucking 19,000 unharmed penguins to Port Elizabeth and making them swim back. Three of the evacuees were fitted with satellite transmitters so their progress around the Cape coast could be tracked. Percy, Peter, and Pamela completed the journey in a little over three weeks, arriving just as the last oil from the tanker was being removed and their island homes declared fit for habitation again.

When I visited Dassen Island, now a nature reserve, the penguins were undergoing their annual molt, during which the entire plumage is replaced over a 21-day period. Because the birds cannot go to sea during this time, they are forced to rely on fat reserves built up during five weeks of binge feeding beforehand. Despite that, they lose nearly half their weight while waiting for their new tuxedos and must go out to sea for a solid six weeks of feeding to recover once the plumage comes in. Standing about in groups of a few dozen, the birds looked stoic as they endured their three weeks of bad-feather days. As I watched them, I thought of the centuries of guano scraping, egg collecting, and penguin harvesting that have gone on up and down this coast—to say nothing of seal clubbing and whale harpooning. With great abundance comes great exploitation, and South Africa has known both.

My two-ocean traverse of South Africa's coast—from the coral fiestas of Sodwana Bay to the kelp cathedrals of the Cape—left me with a deep respect for the rulers of these seas: the Agulhas Current, which shifts 75 million tons (68 million metric tons) of warm water a second along one coast, and the Benguela system, whose cool, upsurging waters nourish a food chain from plankton to people along the other. It seems only fitting that just as terrestrial Africa—with its lions and elephants, rhinos and zebras—has come to hold an iconic allure, this underwater Africa should come to be seen in a similar vein: the Serengeti of the sea.

Extras: See photos, field notes, and more from this National Geographic article.