Heed caution for our vulnerable humpback dolphin

South Africa's most endangered marine mammal

Buffalo Bay is one of Greater Knysna’s most sought after ocean realms and each year, its relatively calm waters lure many in search of sand and sea therapy. But we are not the only ones drawn to these sublime shores, so too is the Indian Ocean humpback dolphin, a member of the genus Sousa.

If you are a frequent visitor to Buffalo Bay and other nearby spots along this stretch of coastline, you are likely to be rewarded with sightings of both these and the charismatic in-shore bottlenose dolphins. The tragic difference between the two,however, is that while bottlenose dolphins number in their many thousands along much of our Southern African coastline, studies of humpback dolphins estimate that fewer than 1,000 of this species remains, making it South Africa’s most endangered marine mammal.

Until very recently, it was thought that the humpback dolphins seen along our coastline belonged to the Indo-Pacific humpback dolphin (S. chinensis) genus, but scientific genetic studies have shown that they are in fact an entirely different species, namely, the Indian Ocean humpback dolphin (Sousa plumbea). These are further divided into 2 different sub-populations with very slight genetic variations. One of them occurs in waters between False Bay and Algoa Bay, the other can be found along the KwaZulu-Natal coast. The IUCN Red List still considers S. chinensis and S. plumbea as one type and lists them as ‘near threatened’ because globally they are thought to number only 10,000 adult individuals. However, when considering S.plumbea separately, the species is considered internationally ‘Vulnerable’.

Indian Ocean humpbacks are medium sized dolphins, measuring up to 2.5m long, and are easily identified by the prominent hump and elongated dorsal fin on their backs. This shy, shallow water type is usually found congregating in small groups (usually no more than 10), mostly around rocky reefs or sand gullies, remaining mostly within 400 meters of the shore in waters rarely more than 30 metres in depth. This very fact makes them extremely vulnerable to the negative influence of humans such as bad fishing practices, pollution, shark nets (one of the key contributors to the decline of these animals) and negligent boat users.

People that navigate vessels close to shore need to be mindful and vigilant of this extremely vulnerable species which finds sanctuary here. In late March, during an Eco Marine Tour, we happened upon a small number of humpback dolphins in Buffalo Bay and only noticed later, whilst editing the photos, that one of the individuals had what appeared to be a boat propeller inflicted injury on its dorsal fin.

Humpback dolphins are very shy animals and this fact along with their small pod sizes makes them often very difficult to spot. Fishing and recreational vessels operating in this area should therefore approach the shallower waters near Buffalo Bay and surrounding areas with extreme caution. If the vessel is within 300m of a dolphin, all efforts should be made not to be intrusive. Only official permit holders are allowed to approach these animals and they are guided by very strict regulations according to each individual species.

Let us all do everything in our power to help save this vulnerable species from extinction….

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Beautiful and rare humpback dolphin swimming in Buffalo Bay

 

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Indian Ocean humpback dolphins are easily identifiable from the hump on their dorsal fin.

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Mother and calf swimming side by side. It is always so heartwarming to see babies, considering the low population numbers.

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Note the wound on the back of this dolphin’s dorsal fin.

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An image of three humpback dolphins swimming within Buffalo Bay, note how close they are to shore.

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