Whales and dolphins of South Africa – Join a whale and dolphin watching tour with Oceans Africa.
Whales and dolphins (Cetacea) can be divided into two major groups or sub-orders. Baleen whales (Mysticetes) are distinctive for having two blowholes and whalebone (baleen) plates hanging from the roof of the mouth to filter food. The rorqual whales – from the Norwegian ‘rorhval ‘meaning furrow – are also of this group and are distinct once again for having a series of longitudinal grooves or pleats, extending from under the throat to behind the pectoral fins. These groves allow the throat to expand – concertina style – and hugely increase capacity whilst feeding. Toothed whales (Odontocetes) have only one blowhole and by definition have teeth. Dolphins are in fact small, toothed whales of the family Delphinidae. All species of Cetacea have a horizontally flattened tail (fluke) and flattened forelimbs forming the pectoral fins whilst most species have a boneless (dorsal) fin on the back.
Cetaceans breathe using lungs and therefore rely on air from the surface – they are highly specialised, intelligent and totally aquatic mammals. They can produce a large and varying vocabulary of sounds as a means of communication and in many species, a form of echo-location.
Many species of whale were hunted to the brink of extinction by the mid 1960’s – see history of whaling. Recent conservation efforts have seen a steady and encouraging rise in some cetacean populations, in particular those of the southern right and humpback whales, however the conservation status of most species is at present unsure and must be regarded as still vulnerable. Since 1986 over 23 000 whales are known to have been hunted and killed. Another major concern is the current threat from commercial fishing practices, gill nets and pollution, to the many species of dolphin that inhabit coastal waters worldwide.
HUMPBACK WHALE – Megaptera novaeangliae.
Identification: Humpback whales have distendable throat grooves and are therefore classed as rorquals (family Balaenopteridae). They are however, significantly different in appearance and biology to all the other rorqual species and as such, represent a separate, single species genus – Megaptera. Humpback whales have a small dorsal fin about two thirds of the way down the body, which is set upon a gradually sloping hump – more noticeable when the animal dives. Most distinctively however, are the unusually long, often white, pectoral fins, in stark contrast against the almost black upper body. These pectorals can be as much as one third of the total body length and provide the scientific name – Megaptera meaning large wing. The underside of the fluke also tends to be white and the distinct patternation on individual animals can be used by scientists for identification. On the large head are three rows of tubercles, known to the old whalers as “stovebolts”. These are also found on the lower jaw and accumulate at it’s tip. Humpback whales as large as 18m have been recorded although specimens in the southern hemisphere tend to be smaller.
Biology: Females reach sexual maturity at about 12 meters and like all baleen whales they tend to be larger than the males of equivalent age. Gestation lasts between 11 and 12 months and generally produces a single calf which is then suckled for a period of 10 to 11 months.
Behaviour: Southern ocean stocks of humpback whales feed almost exclusively on krill near the polar regions and are known to create bubble nets in order to concentrate their prey. Sightings in South Africa are not unusual from June to Janurary as the whales migrate up the east coast to calve and mate in the waters off Mozambique and Madagascar. Although humpback whales appear not to feed when in tropical waters, it is believed they may feed opportunistically on the journey back to Antarctic regions. During this period the whales are merely passing our coastline but we often find them offshore in small groups (of upto 10 animals) or singly and with calves.
Humpback whales are able to launch their entire body clear of the water and have been recorded breaching over 100 times in succession. They are also the most ‘vocal’ of all whales and if you dive in South Africa during the winter months you may well hear the haunting songs of the humpback whale, although the animals themselves can be several kilometers away. Only the males sing long, elaborate, songs which can last up to 20 minutes and may be repeated for several hours at a time. Research has shown that these songs, which are gradually modified over time, are learnt and passed on to other whales within specific populations – an example of whale culture similar to that in evidence amongst many species of toothed whale.
SOUTHERN RIGHT WHALE – Eubalaena australis.
Identification: Southern right whales have no dorsal fin. The large rotund body, attaining 16m and a weight of 65 tonnes, is mostly black with some individuals appearing mottled. The mouth of the southern right whale describes a high arch and the head bears numerous warty growths known as callosities. These growths form a unique patternation amongst individuals and are a useful means of identification. Southern right whales have a distinctive blow and can be immediately recognised from the surface by their V-shaped spout upon exhalation.
Biology: Southern right whales are biologically very similar to their northern cousins, the… wait for it… northern right whales. Competition between males is non-agressive as several males will mate with the female and fertilisation is achieved by the largest sperm count – hardly surprising then that the testicles can weigh in at 500kg each. Gestation lasts between 11 and 12 months, producing a single calf which is then suckled for at least six months. The calf may consume a staggering 600 litres of milk per day in preparation for the journey south into colder waters. Calves can be as large as five meters and five tonnes at birth, and may grow as much as 2.5cm per day. A small percentage of southern right calves (invariably males) are born entirely white or mottled and will gradually turn grey with age.
Behaviour: Inhabiting all southern oceans, southern right whales feed selectively on copepods and krill during the summer months. They migrate north during winter to calve and mate in sheltered bays up as far as the tropics. As with the humpback whale, southern right whales appear only to feed opportunistically in the warmer temperate waters. Evidence now suggests that individuals return to South Africa each year and sightings reach a peak between August and October but are not unusual from June to November. At the peak in 2001 over 50 individuals were recorded simultaneously in Plettenberg Bay alone. Once reduced to a mere 10% of their original population, southern right whales were the foundation of the whaling industry in the 1800’s. During this time and being the ‘right’ whales to kill, the stock declined rapidly as the catch comprised of many adult females, either pregnant or with calves – see history of whaling. The population of southern right whales is now increasing exponentially at the very encouraging rate of 7% per annum. At this continued rate we can expect the population to double within the next ten years.
BRYDE’S WHALE – Balaenoptera edeni.
Identification: Bryde’s whales can attain 14m and 20 tonnes. The body is sleek and dark-grey to mottled with a lighter underbelly. They have a prominent erect and hooked dorsal fin approx. three quarters down the body. When seen from the surface they can be difficult to distinguish from the minke and sei whales, however they have three distinct ridges along the top jaw which are not found in the other species.
Biology: Little is known. Gestation seems to be about a year and the resulting calf is then nurtured for another year before the female falls pregnant once again. Sexual maturity is reached at 12m for males and 13m for females after between 7 and 13 years.
Behaviour: There appear to be two populations off the Western and Eastern Cape – one remaining mostly offshore and migrating seasonally, while the other population is more or less resident in shallower waters. Bryde’s whales feed on small crustaceans and shoaling fish, often scooping up huge mouthfuls by lunging up from depth. Being elusive animals, they tend to shy away from boats and seldom provide a good sighting unless feeding, although this year (2003), a particular individual has shown more than just a passing curiosity in our boat. Sightings of Bryde’s whales are most common from late Summer into Winter when they are often seen “‘running” with common dolphins or when shoaling fish are closest to the shore – see the sardine run.
MINKE WHALE – Balaenoptera acutorastrata.
Identification: Minke whales are the most abundant and smallest of all baleen whales – attaining only 10m in length. The sleek, dark-grey upper body becomes lighter towards an almost white underbelly. The pectoral fins bear a distinctive white band and the dorsal fin is prominent and erect. When seen from above the head is distinctly pointed and resembles a V-shape.
Biology: Little is known. Gestation lasts about eleven months and the calf is nurtured for approx. five months. They reach sexual maturity at a length of around 7m.
Behaviour: Minke whales are mostly solitary animals. They can be found in temperate, coastal waters up to the tropics, although adults often spend the summer months in the feeding grounds of the Antarctic. They feed on small crustaceans and shoaling fish, tending to smash through shoals along the surface, unlike the brydes whales which often lunge up from below. Still hunted by certain countries, the “‘acceptable” quota is adjusted annualy as minke whales are one of the least endangered of all whales. Sightings are rare in southern Africa.
BLUE WHALE – Balaenoptera musculus.
Identification: The blue whale, the largest organism on our planet is also the largest animal ever to have lived on our planet. Adults can reach almost 30m in length and weigh up to 100 tonnes. The body is slender, blue-grey and mottled in colour, with a small, sickle-shaped dorsal fin approx. three quarters towards the tail. When viewed from above, the head is broad and pointed with a ridge running from the tip to the blowhole. The distendable throat has over 40 grooves and the top jaw has over 300 baleen plates on each side to filter food.
Biology: Little is known. It seems that gestation lasts 11 months. The calves are approx. 7m at birth and can weigh between 2 and 3 tonnes. They are suckled for a period of about 7 months and can consume almost 400 litres of milk per day. Sexual maturity is reached at approx. 12 years of age and at a length of 22.5m for males and 24m for females.
Behaviour: Blue whales are found in all open oceans in small populations, though never common. They feed on krill, crustaceans and small schooling fish.
SPERM WHALE – Physeter catodon.
Identification: The sperm whale is a toothed whale and is the most widely recognised – it being the archetypal whale shape of myth and legend. Female spem whales tend to be smaller than the males which can attain 18m in length and weigh up to 45 tonnes. The body shape is unmistakable. The large square head is almost one third of the total body length. There is no distinct dorsal fin but, instead a series of ‘bumps’ are visible along the back and towards the tail. The pectoral fins are small, broad and rounded. The lower jaw is long and narrow with 18-25 large conical teeth that fit into sockets on the upper jaw. The single blow hole, located towards the front, left side of the forehead is s-shaped and produces a characteristic blow – forward and to the left. Colour can be blue-grey to light-brown to – legend has it – completely white in old age.
Biology: The gestation period of sperm whales lasts between 14 and 15 months. The resulting calves are approx. 4m at birth and are suckled for up to 3 years, with an interval between calves of 3-4 years. Sexual maturity is reached at around 10 years of age. Sperm whales were once highly prized for the large quantity and unique properties of the spermaceti oil found in the head – up to 2.5 tonnes in an adult male. This huge spermaceti organ dominates the vast head and focuses the click sounds and sonic pulses that the whale uses to echolocate and communicate. It is also thought that this organ may serve an important function as the animal dives and might even act as some form of buoyancy regulator at depth.
Behaviour: Found in all open oceans, sperm whales feed on giant squid, octopus and fish. They are completely adapted to deeper waters and are seldom found in coastal regions. The greatest freedivers of all, sperm whales have been recorded at depths of over 3000m, while remaining submerged for over two hours before surfacing.
Sperm whales are born into a matriarchal social unit. Most females will spend the rest of their lives within that unit, while the males will leave the group at about six years of age to form temporary bachelor groups, before becoming more solitary as they grow older.
Scientists have found that different groups of sperm whales consistently make different patterns of sounds. These click patterns, specific to particular ‘clans’ (consisting of thousands of animals) are thought to be passed on through social learning and as such provide further evidence of whale culture.
ORCA or KILLER WHALE – Orcinus orca.
Identification: Unmistakable – you’ve all seen ‘Free Willy’. The orca is the largest of all dolphins, attaining 9m and 8 tonnes. Orcas are most distinctive from the surface for having a huge dorsal fin – larger in males (up to 2m) than in females. The body is robust and glossy-black with distinctive, white markings. There are 10-12 large, conical teeth each side of each jaw.
Biology: Orcas breed the year round and calves are born after a 13-16 month period of gestation. They are then suckled for at least one year.
Behaviour: Found in tropical, temperate and polar waters, orcas tend to hunt in packs and often employ ingenious strategies. They feed on squid, fish, birds, seals, sharks, dolphins and even other whales. Unquestionably at the top of the marine food chain, they seem to have enough sense to disregard humans as a viable and sustainable resource. Only one human is known to have been killed by an orca – a trainer killed by a captive animal. The name “killer whale” derives more from their unsociable behaviour towards other species of dolphin and whale. Orcas are periodically sighted off the coast of southern Africa and distinct groups seem to return to specific locations where they target specific prey. Little is known about their migratory habits, although Navy records do indicate year-round activity in South African waters. See 2003 report for orca pictures.
BOTTLENOSE DOLPHIN – Tursiops aduncus & Tursiops truncatus.
Identification: The beak (rostrum) of the bottlenose dolphin, narrows abruptly from the head. The dark upper body fades to an off-white underbelly, however individuals become speckled with age. The dorsal fin is prominent and hooked. Tursiops aduncus is the most frequently observed inshore species, attaining a length of 2.4m. Tursiops truncatus is much larger (over 3m and double the mass) and is not often encountered inshore in South Africa. Truncatus has a more noticably blunt and abruptly sloping forehead with a shorter rostrum.
Biology: Calves are born throughout the year, although births reach a peak during the spring and summer months. A single calf is born after a years gestation. Suckling continues for up to four years and females become sexually mature at approx. ten years – three years sooner than the average male. Both sexes may live for over 40 years although females tend to live longer than males.
Behaviour: Observations of Tursiops aduncus in the Western Cape have identified four distinct group types: Nursery groups consisting of related females and calves – dolphin society is matriarchal: Young adult groups of both sexes – are usually larger and more playful groups: Small groups of 2-4 males – sometimes accompanied by a female: Mixed groups – which may consist of some or all of the above group types. Hunting collectively and feeding on bony fish and squid, group size is often an indication of how much food is available in a particular area. The national average group size is 60 animals, whilst the Garden Route average is double that at 120 animals. The KwaZulu Natal average is only 20 animals, although this may be directly attributed to the dolphin by-catch of the regions shark nets.
The inshore bottlenose dolphins – Tursiops aduncus – can be found year round along the entire coastline east of Cape Town. Of all the dolphin species they are the most inclined to interact with humans. Masters of the surf zone they are always a pleasure to watch. They seem not to be disturbed by boats and often bow ride, back-splash and sommersault in their presence. Regarding surfers and divers with only a passing curiosity, they do occasionally take time out to teach us some new tricks.
INDO-PACIFIC HUMPBACKED DOLPHIN – Sousa chinensis.
Identification: Humpbacked dolphins attain up to 2.7m in length and have a long, relatively narrow beak (rostrum). The body is robust, dark grey to brown on top and paling underneath. The most distinctive feature is the long shallow hump located beneath a small and hooked dorsal fin. Moving east however, both colouration and form do vary considerably, with the dorsal fin becoming larger on a less obvious hump and the colouration becoming brown and speckled to almost completely white – as found in the pink dolphins of Hong Kong. There is currently much debate as to whether these are now in-fact, two separate species – the Indian humpbacked dolphin (Sousa plumbea) and the Pacific humpbacked dolphin (Sousa chinensis).
Biology: Calves are born throughout the year, but most arrive during the spring and summer months after a 12 month gestation period. Suckling may continue for several years. Females are sexually mature after approx. ten years – three years sooner than the average male and both sexes may live for over 40 years.
Behaviour: Found in temperate to tropical waters the population in Southern Africa is small and estimated at only 1200 animals. Groups of between 3 and 20 humpback dolphins can be found in isolated groups along the entire coastline between Cape Town and Mozambique. Shying away from boats and humans, they hunt close to the shore and feed on reef and estuarine fish. Unfortunately their inshore reliant habits expose them to a higher level of pollution and toxins – run-off from farms and industries inland. Feeding in esturaries and river mouths, they absorb and accumulate these toxins which are then passed on, through the milk to the first-born calf, which is invariably too small to tolerate such levels – a 10 year build up before the female is sexually mature. Subsequent calves will usually survive as the accumulation period of toxins is much shorter – approx. 2 years between calves. Shark nets are also a significant facor in reducing the numbers of such an inshore reliant species.
Current research is trying to establish group movements and at this stage they are thought to be very localised animals. Sightings are year round and the Garden Route affords some of the best opportunities with 120 individuals identified in the area – 10% of the estimated population in southern Africa. Although humpbacked dolphins are notoriously shy of boats and humans they have been known to get used to certain vessels – as seen by those undertaking research – and will occasionally approach and investigate boats. On the rare occasions when they are seen to surf and leap they are unquestionably the most spectacular of acrobats.
LONG-BEAKED COMMON DOLPHIN – Delphinus capensis.
Identification: Common dolphins attain 2.5m, and are less robust in appearance than bottlenose dolphins. The body is dark-brown to black with characteristic, orange-brown, ‘figure of eight’ markings on the sides and a creamy-white underbelly. The head slopes gently forward to a long narrow beak and the dorsal fin is prominent, slightly hooked and triangular. A dark stripe extends up from the pectoral fins to the lower jaw and another joins the back of the beak to around the eye. Click here for pictures of common dolphins
Biology: As with most dolphins, calves are born throughout the year but births peak in summer after approx. one year gestation. They are then suckled for only six months. Females are sexually mature at approx. nine years – two years sooner than the average male. Both sexes may live for over forty years.
Behaviour: Common dolphins are found offshore in most temperate to tropical waters. To be lucky enough to ‘run’ with common dolphins must be considered among the highlights of a lifetime. Common dolphins are usually found in large groups (500 – 3000, although over 9000 were sighted off Plettenbergbay in 1999). They are very gregarious and positively ‘love’ boats. Moving at high speeds whilst chasing prey, they will utilise the bow wave and the wake of a boat in order to save energy. At top speeds (we’ve clocked them at almost 20 knots) they will also ‘porpoise’ and leave the water entirely. Watching common dolphins move through water is to witness apparently effortless motion and the peak of aquatic evolution. Common dolphins are usually only found in the deeper coastal waters, however they are occasionally seen from shore during the summer months in the Western Cape and kwaZulu natal when they follow migrations of schoaling fish up the coast. – see sardine run.