The

KwaZulu-Natal KwaZulu-Natal (, also referred to as KZN) is a Provinces of South Africa, province of South Africa that was created in 1994 when the government merged the Zulu people, Zulu bantustan of KwaZulu ("Place of the Zulu" in Zulu language, Zulu) and ...

sardine run of southern Africa occurs from May through July when billions of

sardine Sardine and pilchard are common names for various species of small, oily forage fish in the herring suborder Clupeoidei. The term "sardine" was first used in English during the early 15th century; a somewhat dubious etymology says it com ...

s – or more specifically the Southern African pilchard '' Sardinops sagax'' – spawn in the cool waters of the

Agulhas Bank The Agulhas Bank (, from Portuguese for Cape Agulhas, ''Cabo das Agulhas'', "Cape of Needles") is a broad, shallow part of the southern African continental shelf which extends up to south of Cape Agulhas before falling steeply to the abyssal pla ...

and move northward along the east coast of

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

. Their sheer numbers create a feeding frenzy along the

coastline A coast (coastline, shoreline, seashore) is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Coasts are influenced by the topography of the surrounding landscape and by aquatic erosion, su ...

. The run, containing millions of individual sardines, occurs when a current of cold water heads north from the Agulhas Bank up to

Mozambique Mozambique, officially the Republic of Mozambique, is a country located in Southeast Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west, and Eswatini and South Afr ...

where it then leaves the coastline and goes further east into the Fisherman are sometimes observed singing songs while hauling in the fishing nets in typical South African style. It is estimated that the sardine run is the biggest Biomass migration in terms of numbers. In terms of

biomass Biomass is a term used in several contexts: in the context of ecology it means living organisms, and in the context of bioenergy it means matter from recently living (but now dead) organisms. In the latter context, there are variations in how ...

, researchers estimate the sardine run could rival East Africa's great

wildebeest Wildebeest ( , ,), also called gnu ( or ), are antelopes of the genus ''Connochaetes'' and native to Eastern and Southern Africa. They belong to the family Bovidae, which includes true antelopes, cattle, goats, sheep, and other even-toed ...

migration. However, little is known of the phenomenon. It is believed that the water temperature has to drop below 21 °C in order for the migration to take place. In 2003, the sardines failed to 'run' for the third time in 23 years. While 2005 saw a good run, 2006 marked another non-run.Sardine Run
The shoals are often more than 7 km long, 1.5 km wide and 30 metres deep and are clearly visible from spotter planes or from the surface. Sardines group together when they are threatened. This instinctual behaviour is a defence mechanism, as lone individuals are more likely to be eaten than when in large groups.

Causes

The sardine run is still poorly understood from an ecological point of view. There have been various hypotheses, sometimes contradictory, that try to explain why and how the run occurs. A recent interpretation of the causes is that the sardine run is most likely a seasonal reproductive migration of a genetically distinct subpopulation of sardine that moves along the coast from the eastern Agulhas Bank to the coast of

in most years if not in every year. Genomic and transcriptomic data indicate that the sardines participating in the run originate from South Africa's cool-temperate Atlantic coast. These are attracted to temporary cold-water upwelling off the south-east coast, and eventually find themselves trapped in subtropical habitat that is too warm for them. The migration is restricted to the inshore waters by the preference of sardine for cooler water and the strong and warm offshore Agulhas Current, which flows in the opposite direction to the migration, and is strongest just off the continental shelf. A band of cooler coastal water and the occurrence of Natal Pulses and break-away eddies make it possible for sardine shoals to overcome their habitat constraints. The importance of these enabling factors is greatest where the continental shelf is narrowest. The presence of eggs off the KwaZulu-Natal coast suggests that sardine stay there for several months and their return migration during late winter to spring is nearly always unnoticeable because it probably occurs at depths where the water is cooler than at the surface. In some years there does not appear to be a sardine run. This may be because it is not detected by coastal observers either because it actually does not occur due to high water temperatures and/or other hydrographic barriers, or the migration may occur farther offshore and possibly deeper due to unusual conditions.

Oceanographic influences

Sardine prefer water temperatures between 14 and 20 °C. Each southern winter the nearshore sea temperature along the South African south east coast drops to within this range. Along the KwaZulu-Natal coast, sardine may be found in water warmer than 20 °C. It was hypothesized that factors beside temperature may influence the movement of sardine along the KwaZulu-Natal coastline, One of these factors may be predation pressure.

Oceanographic regions of the KwaZulu-Natal coast

The KwaZulu-Natal coast includes varied oceanographic regions, each influenced by distinct environmental forces. *The continental shelf waters of the KwaZulu-Natal Mid to Lower South coasts are dominated by the warm Agulhas Current which flows toward the south west. This water has a mean winter temperature of 23 °C and the current speed is often more than 1 m/s within 5 km of the coast. *The Agulhas Current follows a very constant path. The main stream is just offshore of the continental shelf break most of the time, which suggests that conditions are normally unsuitable for sardines along that part of the coast. *Local winds do not appear to have much effect on the currents. *Sardine move closer to shore as they travel northwards along the coast, but it is not known whether this is due to environmental conditions or biological conditions. *There is a persistent cyclonic gyre known as the Durban Eddy, where warm Agulhas Current water flows onto the shelf and the resulting inshore current direction is from south to north. This section of coast may be considered a transition from the wind-dominated section of the continental shelf to the north, to the Agulhas Current dominated section of shelf to the south. *The North Coast section of continental shelf is considerably wider (>40 km) than that of the south coast (roughly 15 km). This causes the Agulhas Current to flow farther offshore, and current conditions over the shelf are more variable. Wind appears to be a dominant influence in the region. Longshore north-easterly or south-westerly winds precede currents of similar direction by roughly 18 hours. Sea temperature is often lower and nutrients higher than along the South Coast. *The North Coast would seem to be more suitable habitat for sardine, but it is not known to what extent they use it. These distinct regions may affect sardine distribution and movement.

Oceanographic variables and sardine presence

Some oceanographic variables have been found useful for describing conditions influencing sardine presence. *Water temperature has an inverse and highly significant influence. This is consistent with the preferred temperature range of sardine. *Sea currents have a significant effect, with calm current conditions most favourable for sardine presence and moderate current speeds from north to south most detrimental. As sardine movement during the run is northwards, this counter-current effect is expected. Other conditions associated with sardine presence are: *Increasing atmospheric pressure: sardine presence appears to be higher during periods between the cold fronts along the KwaZulu-Natal coast. These periods have calm atmospheric conditions and slow nearshore currents. *Large swells and low water clarity associated with cold fronts have a negative effect on sardine presence. *Wind direction, wind speed, current direction, air temperature and rainfall all significantly affect sea surface temperature and consequently sardine presence. *Current and wind direction effects dominated, with north-easterly wind and currents from north to south resulting in cooler sea surface temperatures. *North-easterly winds cause the surface water layer to move away from shore (Ekman veering), allowing the cool water to reach the surface, and south-westerly winds push warm Agulhas Current surface water towards the shore causing inshore temperatures to increase, which would negatively impact upon sardine presence. *Increasing maximum air temperature, south-easterly (onshore) winds, wind speeds in excess of 6 m/s, and rainfall, all result in warmer sea surface temperatures. *Strong south-easterly winds and rainfall are associated with the passage of frontal systems, which would push warm surface waters shoreward resulting in warmer sea surface temperatures. *Frequent light north-westerly land breezes: When north-westerly land breezes are the strongest winds of the day they have a cooling effect on sea surface temperature. This cooling should be greatest in the vicinity of the surf zone where mixing is most effective. Sardine are often sighted close inshore during early mornings, suggesting that they could be attracted by cooler conditions found there.

Summary: Oceanographic predictors of sardine presence

Favourable: *Decreasing sea surface temperature *Calm current conditions *Light north-westerly land breezes *Stable atmospheric conditions. Unfavourable: *Increasing sea surface temperature *Moderate north to south currents *Large swells *Turbid water North-easterly and north-westerly winds and north to south currents have a cooling effect upon nearshore sea surface temperatures, but south-easterly winds and increasing air temperatures cause nearshore sea surface temperature warming.

Predators

Dolphins (estimated as being up to 18,000 in number, mostly the

common dolphin The common dolphin (''Delphinus delphis'') is the most abundant cetacean in the world, with a global population of about six million. Despite this fact and its vernacular name, the common dolphin is not thought of as the archetypal dolphin, wit ...

(''Delphinus capensis'')) are largely responsible for rounding up the sardines into bait balls. These

bait ball A bait ball, or baitball, occurs when small fish swarm in a tightly packed spherical formation about a common centre. It is a last-ditch defensive measure adopted by small schooling fish when they are threatened by predators. Small schooling f ...

s can be 10–20 metres in diameter and extend to a depth of 10 metres. The bait balls are short lived and seldom last longer than 10 minutes. Once the sardines are rounded up, sharks (primarily the bronze whaler), and birds (like the Cape gannet), and

Bryde's whale Bryde's whale ( ), or the Bryde's whale complex, putatively comprises three species of rorqual and possibly four. The "complex" means the number and classification remain unclear because of a lack of definitive information and research. The c ...

s take advantage of the opportunity. Other whale species, regardless of whether they do or not join the run, may appear in the vicinity such as humpback, southern right, and

minke whale The minke whale (), or lesser rorqual, is a species complex of baleen whale. The two species of minke whale are the common (or northern) minke whale and the Antarctic (or southern) minke whale. The minke whale was first described by the Danish na ...

Predators as predictors of sardine presence

The Cape gannet is the predator species most closely associated with sardine presence along the Eastern Cape and KwaZulu-Natal coastline and is the most useful indicator of sardine run activity. Sharks and large gamefish presence is also strongly associated with sardine presence during the run, but as they are not as easily observed from the surface they are not as useful a predictor of sardine presence. The presence of common dolphins inshore along the east coast during winter is significantly associated with sardine presence, and the common dolphin can be considered the third most useful species for predicting sardine presence. The resident population of

bottlenose dolphin The bottlenose dolphin is a toothed whale in the genus ''Tursiops''. They are common, cosmopolitan members of the family Delphinidae, the family of oceanic dolphins. Molecular studies show the genus contains three species: the common bot ...

does not appear to associate with the sardine run, whereas the migrant stock does. This may explain why the bottlenose dolphin is less likely to predict sardine presence.

Record of predators

2005 records: In June and July 2005 the avian and mammal predators included Bryde’s whale (''

Balaenoptera edeni Bryde's whale ( ), or the Bryde's whale complex, putatively comprises three species of rorqual and possibly four. The "complex" means the number and classification remain unclear because of a lack of definitive information and research. The co ...

''), African penguin (''

Spheniscus demersus The African penguin (''Spheniscus demersus''), also known as Cape penguin or South African penguin, is a species of penguin confined to southern African waters. It is the only penguin found in the Old World. Like all penguins, it is flightless, ...

''), Cape cormorant (''

Phalacrocorax capensis The Cape cormorant or Cape shag (''Phalacrocorax capensis'') is a bird endemic to the southwestern coasts of Africa. It breeds from the coastal area of Namibia to southern Western Cape. In the nonbreeding season, it may be found as far north as ...

''), which were predominantly found in the cooler southern part of the region. Peak sardine run activity occurred within 4 km of shore at the northward limit of a strip of cool water (<21 °C) stretching along the East Coast. The principal predators at this stage were common dolphins (''Delphinus capensis'') and Cape gannets (''Morus capensis'').

Economic importance

Tourism

The recent interest in the sardine run has had significant impact on the local economy. International and domestic divers join local tour operators on sardine run diving expeditions. Such expeditions run from Eastern Cape towns, includin
East London
Port Saint Johns, and Port Elizabeth. The run has become important to tourism and is considered to be one of the main attractions in KwaZulu-Natal during the winter holiday period. Both local and international tourists are attracted to the spectacle and are provided with opportunities to participate in activities such as dive charters and boat based predator viewing tours. The

KwaZulu-Natal Sharks Board A notice at a beach protected by the Board The KwaZulu-Natal Sharks Board (KZNSB), previously the Natal Sharks Board and Natal Anti-Shark Measures Board is an organisation that maintains a "shark control" program (using shark nets and drum line ...

and East Coast Radio, facilitate a ‘Sardine Run Hotline’, which provides information on the position and movement of sardine shoals. Information is also provided on the internet. The Sardine Run Association (www.thesardinerunassociation.org) has been formed to provide a link betwee
tour operators
tourists, non-governmental organisations, scientists, and local and national governments.

Fishery

The sardine run also supports a small-scale, seasonal beach

seine The Seine ( , ) is a river in northern France. Its drainage basin is in the Paris Basin (a geological relative lowland) covering most of northern France. It rises at Source-Seine, northwest of Dijon in northeastern France in the Langres plat ...

fishery.

Threats to the sardine run

Climate change and

overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing Fish stocks, fish stock), resu ...

have caused yearly stocks to dwindle, putting endangered species such as the

African penguin The African penguin (''Spheniscus demersus''), also known as Cape penguin or South African penguin, is a species of penguin confined to southern African waters. It is the only penguin found in the Old World. Like all penguins, it is flightless, ...

Cape cormorant The Cape cormorant or Cape shag (''Phalacrocorax capensis'') is a bird endemic to the southwestern coasts of Africa. It breeds from the coastal area of Namibia Namibia, officially the Republic of Namibia, is a country on the west coast o ...

, Cape gannet, and school shark (whose diets consist mainly of sardines) at greater risk of extinction. As the sardines move along a channel of cold water, warming waters could cause the sardine run to cease to exist within a few decades.

History

The oldest known record of the run is a mention in the Natal Mercury newspaper of 4 August 1853. More recently, the run has been the subject of natural history documentaries (e.g., the BBC’s Nature's Great Events) and printed popular media (e.g.,

National Geographic ''National Geographic'' (formerly ''The National Geographic Magazine'', sometimes branded as ''Nat Geo'') is an American monthly magazine published by National Geographic Partners. The magazine was founded in 1888 as a scholarly journal, nine ...

The 2011 run

Pilot shoals were netted at Hibberdene on 20 June 2011, while the main shoal was sighted near Port St. Johns. Small pockets of sardines were seen between Mfazazana and

Margate Margate is a seaside resort, seaside town in the Thanet District of Kent, England. It is located on the north coast of Kent and covers an area of long, north-east of Canterbury and includes Cliftonville, Garlinge, Palm Bay, UK, Palm Bay and W ...

. About 25 crates of sardines were hauled out from the first netting at Hibberdene. A further 33 crates of sardines were netted and were sold at R700 per crate or R30 per dozen sardines. The 58 crates were sold "within minutes".Krishna, C. Upper Coast Fever: ''The sardines are finally here! Early arrivals netted on local beaches'', June 24, 2011. An attempt was also made to net sardines at Banana Beach. About 500

s and numerous sharks were noted near Margate. Shark nets had been removed between Umgababa and Port Edward.Padayachee, K. The Mercury: ''First Trickle of Sardines Netted'', June 21, 2011. Sardines were netted at Park Rynie on 21 June 2011. Some large nets of 200–300 baskets of sardines were taken. The baskets sold at R600 each. A large gathering of sardine predators was seen off Port Grosvenor on the Wild Coast. Thousands of Cape gannets and dolphins were seen in a continuous line of about 6 km between Brazen Head and just north of the Umtata River. It is suspected that this year's shoal is "massive", and will produce a "bumper run". Shark nets have been removed to the south of

Durban Durban ( ; , from meaning "bay, lagoon") is the third-most populous city in South Africa, after Johannesburg and Cape Town, and the largest city in the Provinces of South Africa, province of KwaZulu-Natal. Situated on the east coast of South ...

. The first shoals were expected to reach

Amanzimtoti Amanzimtoti, locally nicknamed Toti, and officially renamed to eManzimtoti, is a coastal town just south of Durban in KwaZulu-Natal, South Africa. Situated along the Sapphire Coast, the town is well known for its warm climate and numerous beach ...

on 23 June 2011.Langa, L. The Mercury
''Bumper sardine run could be just around the corner''
June 22, 2011. The main shoal was still near Port St Johns.Medley, L. Daily News: ''Sardines head for Amanzimtoti'', June 22, 2011. On 22 June 2011, a "few" baskets were netted at Umgababa beach, and a "handful" of baskets were netted at

Warner Beach Warner Beach is a small resort town south of the Little Manzimtoti River in KwaZulu-Natal, South Africa, and it forms part of eThekwini. It was laid out by surveyor P.A. Warner as a residential area in 1910 for government pensioners. History Fre ...

in the afternoon. Sardines were also netted at

Isipingo Isipingo is a town situated south of Durban in KwaZulu-Natal, South Africa and currently forms part of eThekwini Metropolitan Municipality. The town is named after the Siphingo River, which in turn is thought to be named (in the Zulu language) ...

, where 14 baskets were hauled out. The sardines therefore reached the Amanzimtoti area a day earlier than predicted.South Coast Sun
''Early sardine surprise on Upper South Coast''
June 24, 2011. Rough seas (with waves up to 4.7 m) caused by strong winds associated with a

cold front A cold front is the leading edge of a cooler mass of air at ground level that replaces a warmer mass of air and lies within a pronounced surface Trough (meteorology), trough of Low-pressure area, low pressure. It often forms behind an extratropica ...

kept the sardines from the shore on 23 June 2011. Pockets of sardines were seen far out to sea off the Bluff. The rough water and far distance of the sardines from shore made it impossible for the fish to be netted. No dolphin or bird activity was seen in the Durban area associated with the sardines. The main shoal was still suspected to be off the

Eastern Cape The Eastern Cape ( ; ) is one of the nine provinces of South Africa. Its capital is Bhisho, and its largest city is Gqeberha (Port Elizabeth). Due to its climate and nineteenth-century towns, it is a common location for tourists. It is also kno ...

coastline,Daily News: ''Feeling Swell'', June 23, 2011 with a report of some sardines still seen near Port St Johns on 22 and 23 June 2011.Shane's Fishing Blog
''Sardine Run 2011''
retrieved 24 June 2011. Durban beaches were the scene of most netting activity on 27 June 2011. "Hundreds of baskets" of sardines were hauled onto the beaches in 13 nets. The price per basket was R350 in the morning, but later in the afternoon the price had dropped to R120 per basket.The Mercury: ''Rich Bounty'', June 28, 2011. Each net contained in excess of 300 baskets of sardines, with one net containing around 500 baskets.The Citizen: ''Sardine run at fever pitch off South Coast'', 29 June 2011. Sardines were also netted at Umhlanga,

Port Shepstone Port Shepstone is a large town situated on the mouth of the Mzimkhulu River, the largest river on the KwaZulu-Natal South Coast of South Africa. It is located halfway between Hibberdene and Margate, KwaZulu-Natal, Margate and is positioned 120&nbs ...

, Margate, Umgababa, and Port Edward. Cape gannets and other seabirds were seen "plunging from considerable heights" to catch the sardines, especially on the South Coast.Daily News: ''Sardines all along the coastline'', June 27, 2011. Most of the sardines were netted along the Durban beaches as this was the area of calmest waters; swells along the KwaZulu-Natal coastline were around 2.5 m.Daily News: ''Swells drop and sardines are there!'', June 28, 2011 Shark nets had been removed from

Salt Rock Salt Rock is a small coastal village just north of Ballito and Shaka's Rock situated along the Dolphin Coast of KwaZulu-Natal, South Africa. It is a favorite holiday destination for many local South Africans. It is approximately located 52 k ...

to Port Edward, and bathers were requested to consult with lifeguards before entering the water. Meanwhile, a baby dolphin washed up on the beach at Scottburgh, with a gash behind its "flipper" (the photo showed a gash between the dorsal fin and the tail) that exposed the spine. The "weeks old" dolphin was taken to a nearby paddling pool, but authorities later euthanased it due to the severity of the injuries.Upper Coast Fever: ''Little Lost Stranger'', July 1, 2011. Speculation was that the dolphin had been injured by a shark, or by a boat propeller; possibly related to the sardine run. Swells dropped to 1–1.5 m on 28 June 2011, allowing more netting of sardines. Sardines were netted at Amanzimtoti; on the main beach and at Chain Rocks. A 22-year-old American marine biology student (research diver) named Paulo Edward Stanchi was attacked by a large dusky shark while diving at Aliwal Shoal Marine Protected Area. The group of divers had encountered a pocket of sardines when a 3 m long dusky shark bit Mr Stanchi on his left leg and hands. Mr Stanchi managed to free himself from the shark, and was treated on the diving boat before being transported to Rocky Bay, where medics stabilised him. He was then airlifted to Nkosi Albert Luthuli Hospital, where he underwent surgery. Dusky sharks generally live offshore, but come closer to the shore during the sardine run. The annual sardine run allowed more dusky sharks in the Aliwal Shoal MPA than usual, but there was no reason for them to show any more interest in divers than usual. Mr Stanchi had been wearing split fins with black and grey stripes, and this may have looked like a small shoal of fish to the shark.South Coast Sun: ''Shark attacks diver off Aliwal Shoal'', July 1, 2011.Sampson, B. The Citizen: ''Family to visit US shark Attack victim'', 30 June 2011 Meanwhile, a woman in her 40s broke her leg in the frenzy at Amanzimtoti when the sardines were netted. The woman is believed to have been trying to get some of the sardines when she "stepped wrong" and fractured her leg. Paramedics stabilized her before transporting her to hospital.South Coast Sun: ''Sardine frenzy sees woman break her leg'', July 1, 2011. 5 July 2011 was a "quiet day" for the sardine run. "Plenty of birds" were seen diving at Karridene close to the shore. 50 crates of sardines were taken at Umgababa in the early afternoon, while a net of sardines pulled in at Karridene contained some Garrick. More Garrick were caught by fishermen at Karridene, but in general there was little other

game fish Game fish, sport fish or quarry refer to popular fish species pursued by recreational fishing, recreational fishers (typically angling, anglers), and can be freshwater fish, freshwater or saltwater fish. Game fish can be fish as food, eaten aft ...

activity. There was reported to be a "massive shoal" of sardines off Coffee Bay in the Eastern Cape.Daily News: ''Quiet Day disappoints anglers, but main shoal on its way'', July 6, 2011. On 15 July 2011, 100 baskets were netted at Pennington. It was difficult to predict the sardines' movements as they were staying offshore.Waterworth, T. The Independent on Saturday: ''Fishing Tragedy Averted'', 16 July 2011. On 20 July 2011, 300 baskets of sardines were netted at Pennington in the morning. There were many gannets off

Ballito Ballito is an affluent coastal town located in KwaZulu-Natal, South Africa. Ballito is about north of Durban and 24 kilometres (15 mi) south of KwaDukuza. It forms part of the KwaDukuza Local Municipality, and iLembe District Municipality. ...

, and "quite a bit of fish" between Park Rynie and Mtwalume.Medley, L. Daily News: ''Sardine surges almost at an end'', July 20, 2011 A strong

hit South Africa towards the end of July, causing land surface temperatures to drop below 10 °C over much of the country.IOL News: ''Cold front hits SA'': http://www.iol.co.za/news/south-africa/cold-front-hits-sa-1.1108277, retrieved 23 August 2011. Heavy

snow Snow consists of individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water througho ...

falls were experienced in high lying areas, including Nottingham Road, Mooi River and

Newcastle Newcastle usually refers to: *Newcastle upon Tyne, a city and metropolitan borough in Tyne and Wear, England, United Kingdom *Newcastle-under-Lyme, a town in Staffordshire, England, United Kingdom *Newcastle, New South Wales, a metropolitan area ...

in the Midlands, while Van Reenen’s Pass was snowed in.The Ridge Online
''Cold front hits Durban''
retrieved 23 August 2011. The cold front caused swells of up to 4 meters on the KwaZulu-Natal coast and a 25 to 30 knot wind with rough sea conditions. A ship called the Phoenix ran aground at Salt Rock, Ballito on 26 July 2011 because of the rough conditions. This cold front may have put an end to the 2011 Sardine Run.

The 2023 run

The 2023 run has been estimated as being the biggest on observed records to date.

References

External links

{{fishery science topics, expanded=science Aquatic ecology Marine biology Fish migrations . .