3 February 2021
15
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MY ENVIRONMENT
A deep dive into the Dolphins of the Cape Coast – Part 1 These dolphins are occasionally seen in Walker Bay and have a comparatively small home range compared to most dolphins. Some Humpback Dolphins have a home range of only 30km. They can often be found feeding along rocky reef systems and are even known to go up the Breede River! These dolphins tend to stick in shallow waters of not much more than 20m of depth and are a similar size to that of the Common and Bottlenose dolphins in the area.
By Jax Bath
W
hen most people think dolphin, they think Flipper. Flipper was a Bottlenose dolphin which stole the hearts of people around the world. This made the Bottlenose dolphin a household name and perhaps the only species that most people could name off the top of their head. The world of Delphinidae is however a diverse one, with over 40 different species of dolphin roaming our earth’s oceans and rivers. Dolphins are considered to be toothed whales and use echolocation as a means to locate their food. They are typically thought to be more social than baleen filter-feeding whales, and have one blow hole at the top of their head, whereas baleen whales have two. Off the Cape coast, there are six species of dolphin that one might encounter on a whale watching excursion or even from the rocky cliffs that grace our coastline. For this week’s ocean story, I thought I might detail three of the species, followed by the other three next week. I have chosen to do so in no particular order, apart from beginning with my all-time favourite.
Their babies are born at a size of around 1m in length and can spend up to four years with their mother. Indian Ocean Humpback dolphins are also thought to be long lived, with some studies estimating that they could live for over 40 years.
2. The Orca These large beauties are next on the list due to most people not knowing that an Orca is, in fact, a dolphin. They are the largest dolphin species out there, with males reaching a length of up to 9m. Orcas are unlike any other ocean-going creature, so they’re pretty hard to confuse with other species. Orcas are black with white patches and males boast a dorsal fin that can grow up to 2m tall. In Walker Bay, Orcas are typically spotted a few times a year, making them a rare treat. These toothed whales are highly social, often living in matriarchal family groups. The groups seen in our area are typically hunting Common dolphins, though we have two naughty boys, Port and Starboard, who come into the area too in order to feast on sharks. Orcas live complex lives, with different eco types exhibiting different cultures and languages. Though we don’t know all that much about the Orca along the South African coastline just yet, scientists from Sea Search are studying them to get a better idea of what these giant sea pandas are getting up to. In this past week, Sea Search recorded their first ever vocalisation from an Orca in South Africa, which can be found here: https://www.youtube.com/watch?v=0Rq-GnwbXek&feature=youtu.be&fbclid=IwAR0CLP1fLaPWtza9mzRQ_iIO8a5KaLgHwINF6WKo6Q-vBS7ztxxWOZduUr0
1. The Common Dolphin These exquisite creatures are hard to confuse with any other dolphin in the region, as they sport a gorgeous golden patch on either side of their body, running from their eyes to their flanks. These dolphins rule the open ocean, travelling thousands of kilometres in a year and sometimes forming super pods of up to 10 000 animals. They can travel at speeds of over 30km/h, which allows them to cover great distances. Walker Bay is a great area to watch them, with pods heading through the area in the hopes of finding a meal. Simon’s Town and the Cape Peninsula also boast great sightings where they can often be seen from shore if you find yourself a high enough vantage point. These dolphins can be seen year-round, though their presence increases around March/April when the sardines begin their annual migration east. The dolphins follow the sardines, sometimes resulting in a “burning water” scene to rival that of Blue Planet. In addition to sardines, studies have found over 30 different species of fish and cephalopod species in their stomachs. Common dolphins tend to love boats and if you’re ever lucky enough to encounter them whilst whale watching, be sure to listen out for their high-pitched whistles!
Next week’s ocean story will cover the last three species commonly sighted in the Cape: the Bottlenose, Heaviside and Dusky dolphins. Although these are the species most frequently encountered, it’s important to note that there are other species passing through our waters that we’re simply not seeing. Many of the other species travel far away from the coastline but may be encountered by ships and fishing vessels. Evidence of these species also comes in the form of strandings where rarer animals will wash up along the shoreline. The late Peter Best documented 25 members of the Delphinidae family in what he described as the South African sub-region. PHOTOS: Jax Bath
3. The Indian Ocean Humpback Dolphin Perhaps the strangest looking dolphin along our coastline, the Indian Ocean Humpback Dolphin is also the most endangered. There are said to be fewer than 500 of these coastal-dwelling dolphins left in South Africa. They get their name from their fat hump beneath their dorsal fin. This fin can be used to identify the animals, with every dolphin having unique markings. They are a shy species and can be seen alone or in small groups, typically numbering no more than 10 individuals.
