The flipside: The Indo-pacific humpback dolphin

indodolphinThe Breede is abound with an array of fascinating species, all equally in need of protection and attention. However, it is difficult to cover every wriggling bloodworm, grunting grunter and blade of grass. Traditional management has used the single species approach, focusing efforts on a singular species, however this method is outdated. Modern conservation efforts choose to focus on the ecosystem as a whole- the ecosystem approach, by protecting the system you automatically protect an abundance of species. Conservation on the Breede uses this approach. Methods are employed that protect an area and in turn this protects a range of species. Monitoring efforts, the method of observing species for timely detections of changes, are made to observe an ecosystem not individual species. However, there are exceptions to every rule and in the case of the Breede Estuary the humpback dolphin (Sousa plumbea) is the exception.

The dolphin ecologically can be termed as a flagship species- it brings tourism, melts hearts and effectively brings public awareness to environmental issues, a species that effectively acts as an ambassador, icon or symbol. By protecting the dolphin it can subsequently as an umbrella species- providing protection to other species by being protected. There are reportedly 42 species of dolphin in the world, of these there are four species of humpback dolphin; the Atlantic humpback dolphin (Sousa teuszii) and three types of Indo-Pacific humpback dolphins (S. plumbea, S. chinensis and S. sahulensis). From South Africa to the west coast of India we find Sousa plumbea, and it is the very same species that frequents our Breede River estuary.

The Humpback dolphin is grey with a darker dorsal (top side) than ventral (bottom side). The dolphin appears to be quite stocky with a distinct hump on its back. They can reach up to 2.8m and a weight of 285 kg and are known to live over 40 years. Female humpback dolphins reach sexual maturity at around ten years old and will gestate (be pregnant) for 11-12 months. Whilst they may give birth all year around it mainly occurs in spring and summer, the theory is that this is because there is more food available in these months for mothers to eat so that they may adequately nurse their young.

Humpback dolphins populations seem to have a home range between 120 and 200 km. In South Africa we find the dolphin species from False Bay to Mozambique. The dolphins are usually found in small pods (2-4) however are sometimes found in pods as big as 25. Humpback dolphins prefer shallow waters, as a general rule no deeper than 25 meters so bays, lagoons, estuaries and rocky and coral reefs are their frequent haunts. Here they will feed on small fish, squid and octopuses. Peddemors and Thompson (1994) observed these delightful dolphins catching fish in Mozambique by herding fish into shallow water and beaching themselves to then gorge on their catch.

So what is the humpback dolphins biggest threat? Great white sharks and possibly Orcas are natural predators however other threats are shark nets, fishing gear and bioaccumulation (the buildup of substances like pollutants). Humpback dolphins are threatened by a decrease in their prey, pollution and disturbance.

This dolphin species receives little protections with less than 1000 individuals in South Africa. The humpback dolphin is South Africa’s most endangered dolphin species.

Have you ever seen a humpback dolphin in South Africa? Do you have pictures of humpback dolphins in South Africa?

Submit photographs to www.happywhale.com!

Submit sightings to the LBRC Marine Mammal whatsapp group (email your number to marinemammalspottersbreede@gmail.com) or to www.sousaproject.org!

Remember to include where, how many and what they are doing if you can!

Featured illustration by Uko Gorter