A number of reports have filtered through to the East London Museum to indicate that the annual sardine run has started in earnest. Tell tale sightings of hundreds of gannets moving along the coast (characteristically diving for sardines) and being followed by large schools of dolphins have been noted. The largest recorded activity started last Friday 21st May 2015 at the West Bank area of East London. That same day large numbers of dolphins were spotted following sardines off the Nahoon Point Nature Reserve.
The most prolific species of cetacean sighted to date has been the common bottlenose dolphin, Tursiops truncatus, distinguished by their short, stout beak and large dorsal fin. The other species of dolphin which predates on the sardines are the Indo-Pacific bottlenose dolphins, Tursiops aduncus (having a longer beak than the common bottlenose dolphin and a more uniform dorsal colouration), and the long-beaked common dolphin, Delphinus capensis (distinguished by the distinctive ‘hourglass’ marking on the side).
The mass migration of sardines (more specifically known as the Southern African pilchard Sardinops sagax) move from the Agulhas bank (southern coast) of South Africa northwards along the east coast towards Durban. Utilising colder water the sardines are rounded up into ‘bait balls’ by predatory marine species such as the dolphins and their presence noted from the shore by hundreds of gannets diving in to feed.
Conditions conducive to the sardine run include calm sea conditions (including current activity), atmospheric conditions which are reasonably stable (associated with NW land breezes) and decreasing sea surface temperatures.
Predictions are that the 2015 sardine will be better than in previous years.