SOUTHERN RIGHT WHALE
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Southern Right Whale
Taxonomy
Order: Cetacea
Sub Order: Mysticeti or Mysticetes
Family: Balaenidae
Species: Eubalaena australis
Common name: Southern Right Whale
The sub order Mysticeti (Latin for moustache) has eleven species that
are distinct from the only other sub order, odontocetes, or toothed
whales. The family balaenidae has only three species, southern right,
northern right, and bowhead. Other closely related species include the
pygmy right whale and grey whale that are each in their own distinct
family classification.
Identification
Southern right whales have a large head,
broad back with no fin, strongly arched mouthline, dark rotund body,
irregular white patches on the belly and large paddle-shaped pectorals.
They are slow swimmers and may be inquisitive and approachable. Juveniles
and young can be highly acrobatic. Southern right whales are known to
use their flukes (tail fin) as sails This appears to be a form of play
as they will often swim back to the starting point and do it again.
Paired blowholes widely separated produce a V-shaped blow that may rise
as high as 16ft / 5m.
The head of the whale is covered with growths called callosities which
are located above the eyes, by the blowholes, on the rostrum, and on
the chin and lower mouth line. The largest callosity is on the top of
the rostrum and is referred to as the ‘bonnet’. The callosities
are occupied by barnacles, whale lice, and parasitic worms. Whale lice
are actually amphipods, or cyamid crustaceans, and are true parasites
feeding on whale skin and damaged tissue. It is the whale lice that
colour the callosities white, pink, yellow or orange.
The right whales are distinguishable from other baleen whales by their
very long baleen. Baleen is a fibrous curtain of material growing from
the upper jaw and is used for filter feeding. The family balaenidae
is also distinguishable from rorquals (minke, humpback, sei, fin and
blue) by their lack of longitudinal throat grooves which on rorqual
whales extend from immediately under the chin to well posterior to the
line of pectorals.
Size and Weight
Adults are 36 to 59 ft / 11 to 18m
with a weight range from thirty to eighty tonnes. They are slow breeders
with females first calving at 5 to 10 years of age and then giving birth
every 3 to 4 years. Calves are 14 to 20 ft / 4.5 to 6m with a weight
of approximately one tonne.
Distribution
Southern rights occupy the cold waters
of the temperate and subpolar regions of New Zealand, the southern coastlines
of South America, South Africa and Australia.
Diet and Migration
Baleen whales are filter feeders using baleen to sieve out
small planktonic crustaceans. Southern rights are also skim feeders.
They swim on the surface with their gargantuan mouths open allowing
a flow of plankton rich water in through the front of the mouth and
out the sides after filtration through the baleen.
Southern right whales feed mainly or exclusively on copepods, not on
krill which is a common diet for many other whales. Krill, euphausia
superba, are small shrimps between one and two inches long that populate
in the millions during the polar summers.
It is possible that southern right whales, as with other great whales,
have an acoustic map of their world by which they can navigate and identify.
When heading into colder waters for the summer feeding season, southern
right whales stop at the Antarctic Convergence - the invisible line
of temperature change from coolish subantarctic waters to the truly
cold Antarctic krill-bearing waters. After arrival the whales are on
a constant search for widely spaced patches of food.
Mating
By lying on their back, and emitting loud calls,
the female solicits as many males as possible to theoretically ensure
impregnation by the healthiest, strongest male. Upon hearing the familiar
mating call, males will respond from up to five miles away and travel
at a speedy eight to nine knots to reach the female. Up to thirty males
may be attracted at one time and will surround the female while she
is still lying on her back. The strongest males will occupy the best
position, on the sides of the female. In this position, when she rolls
to take a breath, they have the opportunity to penetrate. The males
which have occupied these side positions are displaced every five to
ten minutes and the courtship group can continue for up to four or five
hours.
The successful male is largely determined by both the sperm volume and
timing of entry. The female can put up a difficult chase with many sharp
turns to ensure that only those males with lots of stamina and breath
holding capacity will be able to mate repeatedly.
In the breeding grounds, bellowing sounds and moans are frequently heard
at night.
Calving
Gestation takes twelve to fourteen months, a
little longer than some other great whales. When the calves are borne
they are taken through three different stages of growth prior to their
departure for the Artic summer feeding grounds. In the first month of
their lives they are kept in constant motion by their mothers. Perhaps
because they lack the buoyancy to float without swimming. As they start
to gain buoyancy the second stage involves slower more erratic travelling
and the introduction of play. The third and final stage is a pre migratory
phase which takes place during the last week at the nursery grounds.
During this week there is a sharp decrease in play and a sharp increase
in travel and coordinated movement of mother and calf in preparation
for migration.
Endangered Population
Twelve thousand southern right
whales were taken by whaling operations in the Australian region alone
during the five year period from 1835 to 1839. A further 7,000 were
taken during the following five years. Within a decade, stocks had been
depleted to a level so low that most operations ceased to be commercially
viable and closed. Southern right whales then remained a very rare animal
for more than one hundred years until they became protected in 1937.
They are now still considered rare with a total population estimated
to be between 3,000 and 5,000.
The southern right whale has however had a good population growth rate
of around 7% per annum in recent years, unlike the northern right whale
(eubalaena glacialis) which came closer to extinction than any other
large whale. Their population is estimated at only between 300 and 600.
This specie may never recover.
Right whales were originally named by whalers because they were the
‘right’ whales to catch. They were easy to approach, lived
close to the shore, floated when dead and provided large quantities
of oil. They also provided a lot of meat and had very long baleen referred
to as whalebone.