The annual sardine run along South Africa's east coast is not just a local fishing event but a grand natural spectacle attracting global attention. This massive marine migration involves a diverse array of predators and offers a stunning display of nature's interconnectedness. As one of the planet's most impressive marine events, it draws fishermen, tourists, and international film crews eager to witness and capture the frenetic underwater ballet of predators and sardines.
The sardine run is a complex ecological event that goes beyond the simple migration of sardines. It's a time when the marine food chain is on full display, with predators like copper sharks, common dolphins, and Cape gannets following the sardine shoals northward. These predators form an integral part of the spectacle, with dolphins creating "super-pods" to herd the sardines and gannets diving from great heights to snatch their prey from the water.
The sardine run is a dynamic event that significantly impacts the marine ecosystem. It involves a variety of marine animals, including fish, sharks, mammals, and birds. The sardines, or pilchards, are cold-water fish that thrive in nutrient-rich upwelling zones, which are crucial for the growth of phytoplankton and zooplankton—the sardines' primary food sources. These small fish, including anchovies and herrings, are vital to the global fishery, comprising 25% of the world's fish catch by weight, making them the most valuable group of fish FAO Fisheries & Aquaculture Department.
In South Africa, the Western Cape coast boasts a large sardine fishery, with an annual catch of approximately 100,000 tonnes. However, the catch significantly decreases along the Eastern Cape coast to about 7,700 tons and drops even further in Kwa-Zulu Natal to a maximum of 700 tons South African Department of Agriculture, Forestry and Fisheries.
Sardines have a short lifespan of 2-3 years, and their life cycle is closely tied to the Agulhas Banks off the southern Cape coast, where they spawn. The eggs drift with currents into the nutrient-rich waters off the west coast, where they mature into juveniles and eventually migrate back to the Agulhas Banks to complete their life cycle.
The sardine run is influenced by water temperatures, with sardines preferring waters between 14 – 20°C (57 – 68°F). During the winter months, cooler water extends eastwards along the Eastern Cape coast, creating suitable conditions for the sardines. However, if the water temperature exceeds 20°C (68°F), the sardines stay further south or move offshore to cooler depths, making them less accessible to predators and fishermen. This was observed in 2003 when unusually warm sea surface temperatures were recorded off the southern KZN coast South African Journal of Science.
The sardine run is a feast for predators. Over 20,000 common dolphins migrate into KZN waters to herd sardines into bait balls, which are quickly exploited by other predators like gamefish and sharks. Copper sharks, in particular, travel in thousands from cooler southern waters to partake in the bounty. The Cape gannets, which breed in sync with the sardine run, rely on dolphins to drive the sardines to the surface, making them accessible for their spectacular diving feeding strategy.
While approximately 1,000 resident bottlenose dolphins are commonly seen along the KZN coastline, it's the additional 2,000-plus that migrate from the Eastern Cape during winter that may feed more extensively on the sardines. Humpback whales, although not observed feeding on sardines, are regular visitors during their migration, which is one of the longest mammal migrations known, covering up to 8,000 km Marine Mammal Science.
Southern right whales also migrate to the region during winter, but like humpbacks, they do not feed off the KZN coast. In contrast, Bryde’s whales do feed on the sardines, and Cape fur seals follow the sardines from the southern Cape along the Eastern Cape coast.
For those seeking to experience this unique event, specialist operators offer excursions to witness the sardine run up close. The run provides not only a natural spectacle but also an opportunity for scientific study and eco-tourism, contributing to the local economy and global understanding of marine ecosystems.
For more information on planning an adventure to witness the sardine run, contact TerraSea Travel & Tours at 1-800-403-8488 or visit their website www.terrasea.net; E-mail: info@terrasea.net.
