Diving in South Africa/Sardine run
The sardine run occurs most years between May and July when billions of sardines (Southern African pilchard Sardinops sagax) spawn in the cool waters of the Agulhas Bank then and move along the southern coast of South Africa, eastward at first, then northward as they follow the coastline. This migration is followed by large numbers of predators, which provide the main attraction for divers.
The run, containing millions of individual sardines, occurs when during the winter months a cold south to north-flowing current develops off the east coast, moving inshore and counter to the Aghulas current. A part of the sardine population follows this narrow band of cool water north to Port Edward, swimming up between the coast and warm Aghulas current. The numbers vary from year to year, and it is only considered a "run" when the shoals are big enough to be visible at the surface.
North of Port Edward the cold current is restricted by the narrowing continental shelf and the shoals become concentrated in a narrow inshore band of water, as far as Mozambique where it then leaves the coastline and goes further east into the Indian Ocean.
The shoals may be more than 7 km long, 1.5 km wide and 30 meters deep and are clearly visible from spotter planes or from the surface.
Sardines group more closely together when they are threatened. This instinctual behaviour is a defense mechanism, as lone individuals are more likely to be eaten than large groups, but this behaviour also encourages large numbers of predators to follow the shoals.
Thousands of dolphins are largely responsible for rounding up the sardines into bait balls. These bait balls are densely packed masses of fish and can be 10–20 metres in diameter and extend to a depth of 10 metres and may last for up to about 10 minutes. Once the sardines are rounded up, sharks , game fish birds and the occasional whale take advantage of the opportunity. This is the most desirable time for a diver to join the action.
Spotter aircraft are used by some operators to pinpoint the action. Others rely on luck and following the ones who use spotter planes.
The annual northward coastal migration of Humpback whales occurs at much the same time, and may. if you are lucky, provide extra entertainment.
Divers from all over the world travel to South Africa for the sardine run, but it is not known for a reliable schedule, and there is a great deal of waiting and some luck involved.
The sardine hotline on 082 284 9495 gives regular reports and updates on the shoal's progress up the coast. Bookings for boat space are usually made well ahead of time. Dont expect to turn up and get a place on a few hours notice. Book early, and have a flexible schedule. If you will be using your own Scuba set, it is probably better to take a couple of small cylinders than a big one, as you may be climbing in and out of the boat several times as the action moves around. Many photographers will even freedive, to keep mobile, but this limits underwater time. Get fit and practice buoyancy skills. This is all mid-water diving, usually without marker bouys, and usually without a dive leader to show you around. The action is fast and moves around a lot. Good fins and good finning fitness will help you keep up. This is scuba diving where long fins are an advantage if your legs are up to it. Keep drag to a minimum. The water is normally warm enough for wet suits (around 20°C). Avoid bulky BC jackets, dangling hoses and anything else that sticks out to the sides.
The diving is from boats. You will meet your charter boat at the launch site, and travel out to the shoal, where you hope for a bait ball. Depending on the charter conditions, you may free dive or scuba dive with the shoal and the predators
The sardine run is not considered a high risk diving activity, but there are some skills which are necessary for your safety. Probably the most important is good buoyancy skill, as you will be diving at least part of the time over deep water, though the action is mostly near the surface.