THE SARDINE RUN
By Mark Addison
The greatest faunal event on the planet plays out on the East Coast of South Africa in the months of May through July. This phenomenon takes on many phases and undergoes many changes as well as the fact that it travels over more than one thousand kilometres of ocean. The only constant is the inexorable path that the sardines follow to the north at this time of year. Scientific opinion holds that (some of the sardines) move from their home range off the Agulhas Banks at this time of year and (this) part of the total population heads north. A number of parameters then converge to assist in this range extension. The first and possibly the most important is the formation of a cold south to north current that develops close inshore at this time of year. I submit that if you were a sardine even slip streaming the leader would be of little value if there were not this counter current. Your other option would be to swim against the strong Agulhas current, which flows at nearly thirteen kilometres per hour to the south. At this speed, the sardines would not be holidaying in Durban in July but would probably find themselves washed up against the rocky shores of Tristan da Cunha. But seriously, this quirk of nature not only transports the sardines, but also their food source; a plankton named kalenoides and the room temperature of their home waters – being approximately nineteen to twenty one degrees Celsius. The first cold fronts of the season provide further stimulus for the sardines as they surge north whilst being carried by the current and pushed by the cold polar winds that move up the coast at this time of year. Dr. Allan Connell has shown that the sardines’ head back south to their home waters around November and this appears to conclude the cycle. For the bean counters, there are no accurate figures on what tonnages of sardines come up the coast although we do know that the beach seine netters of Kwa-Zulu/Natal account for about 700 tons per year. This is an infinitesimal percentage of the total sardine population and is no reflection of the biomass that enters the coastal waters of Kwa-Zulu/Natal at this time of year. So lets just go with huge and massive in terms of the sardine numbers entering the coastal waters of the Eastern Cape and Kwa-Zulu/Natal. How many sardines do you think there are in a shoal that is fifteen kilometres long, three and a half kilometres wide and nearly forty metres deep? Oh yes – and this is just one of three shoals within a seventy kilometre stretch of the Transkei and Kwa-Zulu/Natal coast that are this size – unbelievable! In the book of scientific opinion on the sardine run this is about as much as we know, but this is also where it gets very interesting because further investigation takes you into the field and the wide world of anecdotal reports from all and sundry. As many people as you speak to, so many opinions will you be entertained with as to where the sardines come from, where they go to and what they do in between. Suffice to say the only constant is that the Sardines will run and run and run. These little silver fish form the butter of the sea and the plankton that they feed on the figurative bread. Bottom line is that it is no fun being number two in the food chain. If one adds twenty thousand common dolphin, five thousand bottlenose dolphin, tens of thousands of gannets, thousands of sharks, hundreds of seals and a plethora of animals ranging from the Bryde’s Whale (the smallest of the Rorqual’s at some twenty tons) to the game fish that arrive from north, south and the east to our erstwhile harmonious ultra marathon for sardines. The harmony is shattered and the chaos that ensues is a visual feast of unsurpassed magnitude. The common dolphin forms huge pods of between three and five thousand animals. They cover wide stretches of the ocean in hunting lines that can extend for a kilometre or more. Should one of the sentinels find the sardines, an eruption of the ocean ensues as the entire pod turn on their axis with military precision and work together to herd the sardine shoal to the surface. (One of the reasons for this) appears to be the fact that (the dolphin) need to breathe and thus, the closer to the surface the better and also the fact that, as sardines can’t fly, there is no escape once they are pinned to the sea surface. It is here that one of the most amazing spectacles of co-operative feeding behaviour takes place. The dolphin’s whirl around the baitball that they have worked to the surface, the gannets - one of the many animal species that take their cue from the common dolphin - start raining into the water and snatch whatever comes within the range of their razor sharp beaks. The copper sharks also join the fray. Having shadowed the commons for hours at a seemingly impossible pace, these greyhounds of the sea join in with a ferocity and selfishness that does little more than perpetuate the ferocious myth of the basic nature of sharks. Seals seemingly take great delight in pirouetting into this baitball and picking off the hapless sardines, one at a time. Add to this frenzy, the spectacle of a Bryde’s whale as it lunges through the centre of the baitball swallowing all in its path! And yet, no sooner has it begun than it comes to an end and the ocean returns to a calm that is so eerie as to make you think that the events you have just witnessed are nothing but a fantastic figment of your imagination. The only reminders are a few scales, an oil patch and the odd feather drifting aimlessly on a still ocean. On reflection, you have to marvel at the agility and ability of all of the above-mentioned hunters. Because I submit that trying to catch sardines in this fashion, despite the ingenuity of the workings of each species in its attack on the baitball, must be like us trying to get an apple out of a giant tub of water. A note to all parents – think about the cruelty of this act before you make the “apple in a tub trick” part of your kids next birthday party! This is what I have seen. Yet, it doesn’t stop here. The Sardines run on and on, still further up the coast. A massive juggernaut rolling and morphing its way up the coast. Once the holding area of Waterfall Bluff in the Transkei is passed, the sardines move up onto the Port Edward shelf and yet another amazing phase in this quest for perpetual motion unfolds. The huge shoals of the south give way to smaller shoals. Their numbers winnowed by the constant onslaught of predation day and night. As relentless as the predation may seem, the ability of the sardines to out produce the appetite of their predators is the key to their survival. The cruel quirk of fate that brings them close to shore does away with the need for the common dolphin to herd them to the surface from deep water so that the robbers that are waiting in the wings can join in. Here, in the shallows, the predators such as the plump bottlenose dolphin, gannets and languid copper sharks do not engage in the desperate and dramatic feeding strategies employed in the deeper waters of the south. By virtue of the shallow water shelf topography, the sardines are compressed into shoals that are perhaps only a few hundred meters in length but only tens of meters wide and fewer deep. The predators feed as and when they wish as these long, snakelike shoals of sardines wind their way north in a lemming-like fashion. The hapless sardines are often squeezed over the sandbanks in their primeval quest and they then become easy prey for the vast number of shore anglers and beach seiners. The frenzy with which man attacks these hapless sardines must seem like a bitter blow to the gut when one is down if you are a sardine. Once netted the sardines are packed into crates to be sold off to the highest bidder. Whether it’s for bait or human consumption; the last frantic and erratic wriggles of the sardines, as they lie squashed on top of each other on the beach, in a medium seven hundred times less dense than the fluid medium that they have just come from, that not only sustained them but gave them form and shape and resistance so as to make their movement fluid and dynamic, pass unnoticed. The sardines are like choreographed ballerinas performing perfect parabolas and circles en masse and yet as one when in the water. The orchestrated magic of the beautiful doughnuts that they form when invaded by a predator and the perfect space accorded any undulation in the seabed is gone – and yet this is what I have seen. Still the sardines run on and on. Despite this constant attack on their number the sardine shoals, move north, perhaps as a remnant of some relic behaviour, perhaps for some other reason that only they know. Some days they are easily found and the activity as intense as I have described and other days for a plethora of reasons not yet fully understood they seem difficult to track down if not impossible – but I am sure they are still there and moving north all the time. The constant recruitment from the south sustains this activity for the period and seemingly, almost as soon as it has begun it is all over. Having witnessed the spectacle of the Sardine Run from the rocky shores of the Transkei to the open beaches of Kwa-Zulu/Natal leaves me with only one goal in mind – next year’s run. The secret’s out and everyone has their number from Sardine hotlines hosted by the Sharks Board to the proverbial hot knife through butter teeth of the copper sharks. This hapless and desperate bid north by these little fish from who knows where, to who knows what and who knows why is over for another year but will keep us all waiting eagerly for the return of the “Greatest Shoal on Earth.”
Marine Animal hit list for Sardine Spectacular:
1. Sea Birds: q Cape Gannet:- Morus capensis, Coastal waters. Seasonal visitor. q Wilson’s Storm Petrel, q Pintado’s Petrel:- Daption capense, Widespread at sea. Common winter visitor q White Chinned Petrel:- Procellaria aequinoctialis, Common offshore and coastal winter bird q Sooty Shearwater:- Puffinus griseus, Common in winter at sea q Fleshfooted Shearwater:- Puffinus carneipes, Southern Indian Ocean. Offshore waters in Agulhas current. Rare. q Black Browed Albatross:- Diomedea melanophoris, Open southern oceans. Common. q Yellow Nosed Albatross:- Diomedea chlororhynchos, Open southern oceans. Common in winter. q Shy Albatross:- Diomedea cauta , Open southern oceans. Fairly common. q Sub- q Antarctic Skua:- 2. Dolphins: q Bottlenose:- Tursiops truncatus, q Common:- Delphinus delphus. 3. Whales: q Humpback:- Megaptera novanglea q Bryde’s:- , q Southern Right:- , q Minke:- . 4. Sharks: q Scalloped hammerhead:- Sphryna lewini, Maximum length thought to be 3.7m. Large numbers of juveniles swim in packs in the surface waters of the KZN coast q Dusky:- Carcharhinus obscurus, attains 3.7m. Found offshore in the warm surface waters. Females come inshore to pup around the same time as the sardine run in KZN. q Blacktip:- Carcharhinus limbatus, attains 2.5m, common inshore from Mozambique to Algoa Bay q Bronze Whaler:- Carcharhinus brachyurus, attains 3m, common temperate water species. Follows the sardine run in winter on the KZN coast. q Ragged Tooth:- Odontaspis taurus, attains 2.9m, common winter visitor to KZN. Comes to KZN to mate and then females move north and males thought to go south. 5. Seals: q Cape Fur
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