Whales of False Bay


Whales of False Bay

Several species of whale come into False Bay and can be seen in the vicinity of Simon's Town. These include Bryde's Whale, the Humpback Whale (which is the one that 'sings') and the Killer Whale, more commonly known as the Orca. By far the most common, however, is the Southern Right Whale.

Southern Right Whales

Scientific Name And Statistics

Scientific Name:Eubalaena Australis
[eu = Greek, right; balaena = Latin, whale; australis = Latin, south]
Family:Balaenidae
Statistics:

Adult females, larger than the males, are on average 15 metres long and weigh about 40-45 tons, while the males are a little smaller at 14 metres.

Description 

The term "right" whale refers to the fact that in the nineteenth century these whales were regarded as the "right" whales to catch, because they were particularly rich in oil, being slow swimmers they were easy to catch, and because their carcases were easy to handle as they floated when dead. It is usually considered that there are two species of "right" whales, one in the northern hemisphere and the other in the southern hemisphere.

Southern right whales are baleen whales. This mean that they have about 200 to 270 pairs of fine 'plates' which hang down from the upper jaw like vertical venetian blinds, through which they filter their food [see under Diet]. These plates may be up to 3 metres (9.5 feet) long.

The most striking feature of the Southern Right whales are the 'callosities' (horny growths) behind the blowholes, and on the face. These provide homes for several other creatures, including the 'whale lice' or cyamids, which live on the callosities and operate in a symbiotic relationship with the whales, feeding off the dead skin. Barnacles burrow 4 cm down into the skin. The other characteristic which distinguishes the Southern Right whales are their V-shaped blows. Southern Right whales are black or dark grey in colour. They have no dorsal fin. They have a large, bow-shaped heads and arched mouths. Unusually, Southern Right whales are relatively hairy with up to 300 hairs on the tip of the lower jaw and about 100 on the upper jaw.

Southern Right whales can remain under water for about 6 minutes and swim fairly slowly at an average speed of 6 kilometres and hour when cruising, although than can reach 11 kilometres an hour in short bursts.

Although the humpback whales are the best "singers", Southern Rights do produce low frequency sounds to communicate with one another.

The lifespan of the Southern Right whale is not established, but it is believed that they can live for over 50 years.

Range & Habitat 

The Southern Right Whale lives between latitudes 20° to 55°, occasionally venturing down to 63°. Although it is to be found throughout the southern oceans, in our part of the world it returns annually to the sheltered bays of the Southern African coast in order to breed and give birth. In False Bay it can be seen between June and November. It is most prolific close to the shore from about September, and it is occasionally seen out of season, as early as May or as late as January.

During the summer months the southern right whales move south to the cold and stormy waters of the Antarctic where it feeds.

Diet 

As baleen whales, right whales swim with their mouths open so that the baleen plates can filter out the water and retain the krill forms a large part of their diet. They eat up to 1½ tons a day of these tiny creatures. They are seasonal feeders, eating in winter and living off their blubber in the breeding months in the north.

Reproduction 

One female southern right whale will mate with a number of males at the same time, with sometimes as many as eight competing for her favour. The male producing the most sperm is probably the father of her baby. Females usually have one calf every three years.

The gestation period (pregnancy) of the southern right is twelve months, she bears her calf in the spring in the warmer waters of southern African bays. Usually only one calf is born although twins sometimes occur. About 3% of calves are born white, but this usually becomes grey after a few months. The calf is born tail first and immediately swims to the surface of the water to take its first breath. Initially it is helped by the mother but within thirty minutes of birth it can swim. The newborn calf is about 4,5 to 5 metres long.

The calf suckles from a pair of teats, sometimes consuming 600 litres of milk a day and growing 2,8 cm a day. It is weaned after about 6-8 months by which time it has reached about 9 metres in length.

Conservation 

Southern right whales are regarded as an endangered species as their numbers have been considerably reduced in the last 200 years. Between 1790 and 1825 it is estimated that over 12 000 southern rights were killed by whalers of the South African coast. Now collisions with ships or entanglement in fishing gear are the main dangers. There are now about 4500 southern right whales, with about 1500 coming to southern Africa. However, southern rights are not as vulnerable as the northern rights which are believed to be close to extinction since they live in more hazardous waters. Moreover, southern rights are increasing in number, doubling in size every ten years, which means that they should have returned to their optimum population size in about 2040.

In 1980 and again in 1984 legislation was introduced in South Africa to protect whales. It is now illegal to shoot at whales, or harass them by coming closer than 300 metres in any craft.

Bryde's Whales

Scientific Name And Statistics

Scientific Name:Balaenoptera Edeni
Family:Balaenidae
Statistics:

Like other baleen whales, mature females are larger than the males, reaching about 14 metres in length, as opposed to the males of 13,5 metres.

Description 

Bryde's whales are distinguised by their prominent "falcate" dorsal fins. They are rorqual whales. This means that they have throat grooves which enable them to open their mouths very wide in order engulf great quantities of water when feeding. However, they are distinguished by three ridges running along the top jaw. The upper body is dark grey, lightening under the belly, becoming white in the centre. There is a slate-grey band across the underside of the body at the end of the throat grooves.

Range & Habitat 

Bryde's whales may be seen along the whole length of the South African coast at any time of the year. However, they are most visible when shoals of small fish are plentiful inshore or in False Bay.

Relatively little is known about Bryde's whales. There seem to be two populations along the South African coast, one of which is "resident" (non-migratory) in inshore, shallow waters, including False Bay. They are usually seen singly although sometimes small groups from when they are feeding. They are not particularly fast swimmers, nor do they dive deeply, usually remaining under water for a only couple of minutes.

Diet 

Bryde's whales feed on large shoals of small fish like pilchards and sardines, in the company of gannets, penguins and dolphins. They zig-zag through the water on their sides, gulping food as they go.

Reproduction 

Little is known of the reproduction of Bryde's whales.

Conservation 

Bryde's whales have not been exploited much by whalers, and as a result, as far as we know, there has not been a serious depletion of their population. 

Humpback Whales

Scientific Name And Statistics

Scientific Name:Megaptera Novaeangliae
[megaptera = huge wings, i.e. the fins]
Family:Balaenopteridae
Statistics:

Adult females are larger than the males. Southern hemisphere Humpback whales are slightly smaller than those of the northern hemisphere, with females reaching 13,7 metres and males 13,1 metres. They weigh 30 to 50 tons.

Description 

The Humpback whale is distinguished particularly by its very long flippers which are almost a third of its body length and is white in colour. The body is black, although it may have white patches, and is fairly short and round. It has a large head on which there are three irregular rows of knobs (tubercules). There are similar projections on each side of the lower jaw, at the tip of which there is a large, rough, wart-like area. Like the Bryde's whales, they are rorqual whales with throat grooves running from the chin to the navel. The dorsal fin is fairly short and thick, set on the long, sloping hump which gives the whale its name. There are two blowholes.

The male humpback whale is particularly notable for the wide range of sounds it produces - moans and screams of varied pitch, lasting up to 30 minutes, and ranging from 20 to 9000 Hertz (females don't sing!) These "songs" differ according to locality and the patterns appear to change from year to year, but seem to occur only in warm waters. It is believed that they are some form of communication.

Humpback whales are the acrobats of the ocean, "breaching" (jumping clear of the water) and "lobtailing" (slapping the water with their tails). They also "spyhop" (poke their heads out of the water). They usually occur singly or in small groups (pods). They remain submerged for about 15 minutes, diving to depths of 150 to 210 metres (500 to 700 feet). Their swimming speed is about 12 kilometres an hour (3 to 9 miles an hour), although speeds of up to 25 kilometres (15 to 16 miles) an hour have been recorded.

Range & Habitat 

Humpback whales are to be found all round the Southern African coast but the two main pods are located off the Angolan and Mozambique coasts. They migrate north in the winter, to mate and breed, largely off the east African coast, with their numbers peaking in June and July.

Diet 

Humpback whales, like other baleen whales, seem to be seasonal feeders but they do eat copepods and fish off the Angolan coast. On average a Humpback whale eats 2000-2500 kilograms of food a day during the feeding season. They co-operate in hunting, rounding up their prey in "bubble-nets". A hunting pod forms a circle under water, then blows a wall of bubbles as it swims to the surface in a spiral path. This cylindrical wall of bubbles traps the prey which the humpbacks devour as they all (whales and prey) move to the surface.

Reproduction 

Humpback whales form only temporary relationships. Females reach sexual maturity when they are about 15 years old and they bear a calf about every three years. The spectacular activities of the humpback whales, breaching and lobtailing, are believed to be courtship rituals. Gestation lasts about a year, with the female giving birth to a single calf, although twins do occur. The calves are about 4,2 metres long when they are born, and they are suckled for about 10 to 11 months. Humpback whales reach puberty after 4 to 7 years.

Conservation 

Because they occur close to the coast and swim fairly slowly, humpback whales have suffered severely from modern whaling. It is estimated that there are about 10 000 to 15 000 whales throughout the world. In South Africa 1963 they received full protection and their numbers do now seem to be increasing.


Killer Whales (Orcas)

Scientific Name And Statistics

Scientific Name:Orcinus Orca
Type:Toothed Whale - Dolphin
Statistics:

Unlike the other whales described here, Orca males are larger than the females, reaching a maximum length of 10 metres, while the females average about 7,5 metres.

Description 

Orcas are the largest dolphins. They have a short, rounded head with a very short beak containing 10 to13 large conical teeth in each jaw. The flippers are broad and well-rounded at the tips. Their dorsal fins get larger as they grow older, and are their most distinguishing characteristic, sometimes reaching 2 metres high in mature males. They have broad flukes (tails) and the upper parts of their bodies are dark, black to brown, while the lower jaws and bellies are white. Behind the eyes there are oval white patches, and others behind the dorsal fins.

Like all dolphins, orcas produce whistling and clicking sounds. It is thought that the whistling is used for communication with other group members, and the clicks for 'echolocating' prey. The effect that the sounds have on other marine animals is dramatic, prompting whales and other dolphins to flee the area, and penguins and seals to head as quickly as they can for land.

Range & Habitat 

Orcas may be found the whole length of the South African coast, including False Bay, but their movements are unpredictable. Little is known of their migratory patterns.

Orcas sometimes form groups of up to 200 animals but in the South African waters they are usually in small groups of 3 or 4. They can attain speeds of up to 30 kilometres and hour and dive for up to 6 or 7 minutes.

Diet 

Orcas have a varied diet, ranging from fish, squid, and sea birds to seals, dolphins and small whales. They have a fearsome reputation as killers and seals appear to have an inborn fear of them. Orca packs appear to disable their mammalian prey by biting the flippers or flukes and then attempt to get to the tongue, which they like particularly. One report claims that the remains of 14 seals and 13 porpoises were found in the stomach of one orca!

Despite their fearsome reputations, there are no records of orcas attacking man. In captivity they are docile and respond well to training.

Reproduction 

In tropical waters orcas seem to mate and calve throughout the year, but in cooler waters these activities are confined to summer. The gestation period is about a year. Calves are about 2.3 metres long at birth and are suckled for about twelve months. Orcas reach sexual maturity at about 12 years of age, when they are about 5 metres long.

Conservation 

It is not known how vulnerable orcas are, although it is suspected that they are endangered.


Further Reading 
Whale Watch - A Guide to Whales and Other Marine Mammals of Southern Africa
Vic Cockroft & Peter Joyces
(Cape Town, Struik, 1998)
Sponsored by MTN and available at most bookshops.