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SPECIES INFORMATION
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Ganges
River dolphin
 Platanista gangetica
Local name - Shushuk
The body of the endangered shushuk is gray or light brown.
Bellies of young animals are lighter and often have a
pinkish hue. These river dolphins have a long snout with
numerous narrow pointed teeth. Their eyes are extremely
small and visible as pin-hole openings slightly above the
upturned mouth. The blowhole is a small slit, which is rare
but not unique among cetaceans. The dorsal fin is a low
triangular hump. The shushuk has large, broad flippers.
The Ganges River dolphins are threatened in Bangladesh from
the effects of dams, large embankment schemes, dredging,
fisheries by-catch, directed hunting, and water pollution.
Local people are familiar with these dolphins swimming in
rivers throughout the country and fishermen generally regard
them favorably as their companions. |
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Irrawaddy
dolphins
Orcaella brevirostris
Local name - Iraboti
Irrawaddy dolphins have a blunt head with no visible
rostrum. The dorsal fin is small, triangular with a rounded
tip. A U-shaped blowhole opens to the front, the opposite of
most dolphin species. Adults range from 2.0-2.75 m and
length at birth is about one meter. The animal is gray
overall with a generally lighter abdomen.
Irrawaddy dolphins generally occur in South and Southeast
Asia in pockets of less than 100 individuals. They are
adapted to nearshore marine environments with freshwater
inputs.
Our research shows that there are more than 5,800 Irrawaddy
dolphins in freshwater affected coastal waters and in
waterways of the Sundarban mangrove forest of Bangladesh.
This means that Bangladesh has the largest Irrawaddy dolphin
population in the world.
These dolphins have been documented accidentally caught in
fishing nets in almost all areas where they have been
studied. |
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Finless
porpoise
Neophocaena phocaenoides
As the name implies, finless porpoises have no dorsal fin.
Adults reach about 1.9 m in length. Their dark grey body is
slender with a rounded head and no beak.
Finless porpoises are generally found as singles, pairs, or
in groups of up to 20. This porpoise occurs in tropical to
warm temperate shallow waters of the Indo-Pacific region,
mostly in coastal waters, including mangrove swamps,
estuaries, and some large rivers. The finless porpoise
prefers areas where rivers and the ocean meet. Our research
has resulted in an estimate of 1,382 individuals in the
coastal waters of Bangladesh. Finless porpoises have also
been sighted in the Sundarbans mangrove forests.
Finless porpoises are extremely susceptible to entanglement
in gillnets, and large numbers continue to be killed
throughout their range. This coastal species also suffers
from serious problems of habitat loss and degradation,
vessel strikes, and environmental contamination.
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Indo-Pacific humpback dolphin
Sousa chinensis
Local name - Golapi
Indo-Pacific hump-backed dolphins have a 2.5 - 3 m long body
and well-defined beak. The dorsal fin sits on a hump in the
middle of the animal's back. The local name indicates its
most apparent characteristic. Calves are dark gray; the
animals turn light cream-colored or pink with increasing
age.
Although groups of humpback dolphins generally contain fewer
than 10 individuals, in Bangladesh groups of up to 40
individuals have been repeatedly observed. Some
subpopulations are threatened by bycatch and habitat loss.
Recent photographs of the species in Bangladesh reveal that
individual dolphins can be identified from visible marks.
This finding opens up new possibilities for understanding
these animals in our waters. |
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Indo-Pacific bottlenose dolphins
Tursiops aduncus
Indian Ocean bottlenose dolphins reach a maximum size of
about 2.5 meters. As their common name suggest, they have a
bottle-like snout. They have relatively large flippers,
dorsal fin and flukes. Their color pattern is basically grey
with a slightly darker cape extending below the dorsal fin.
Dark bluish spotting often extends from the belly to the
throat and around the mouth, especially in older animals.
Bottlenose dolphins in the Swatch-of-No-Ground have been the
focus of a photo-identification study which uses distinctive
marks on the dorsal fin to identify individuals. Almost half
of the dolphins identified from photographs exhibit scars
and mutilations from rope and net entanglement. A population
likely exceeding 1,000 Indo-Pacific bottlenose dolphins
inhabits the marine waters of Bangladesh from the coast to
the over 200 m deep waters along the rim of the
Swatch-of-No-Ground.
Indo-Pacific bottlenose dolphins living along the
Swatch-of-No-Ground take advantage of the high productivity
created by upwelling currents along the canyon edge. The
general absence of Indo-Pacific bottlenose dolphins in
nearshore waters more strongly affected by freshwater flow
may reflect inter-specific competition with Irrawaddy and
Indo-Pacific humpback dolphins and possibly finless
porpoises, species that are perhaps better adapted to
estuarine conditions.
A major emphasis of current conservation efforts is on
reducing mortality and injuries due to interactions with
gillnet and trawl fisheries. |
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Pantropical
spotted dolphin
Stenella attenuata
Pantropical spotted dolphins are slender and streamlined.
Adults are 1.6 to 2.6 m long. They have a long slim beak.
The dorsal fin is narrow, curved and pointed at the tip.
Most adults have spots on their dark dorsal cape, but young
are born without spots. The belly area is a lighter gray.
In Japan large numbers of spotted dolphins are caught for
human consumption. Pantropical spotted dolphins are also
taken in hand-harpoon fisheries in the Philippines and in
gillnet and harpoon fisheries in India and Sri Lanka. Little
is known about the spotted dolphin in Bangladesh. Our
observations imply that significant numbers of the species
may also occur farther offshore in un-surveyed waters of the
Bay of Bengal. |
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Spinner dolphins
Stenella longirostris
Spinner dolphins are between 2 and 2.4 m long, slender with
an extremely long beak. The dorsal fin is slightly curved.
Most spinner populations have a three part color pattern
that includes a dark dorsal cape, light gray sides, and
white belly. They get their name by their habit of leaping
and spinning.
Spinner dolphins often occur in very large groups hundreds
of kilometers from the nearest land. They are often found in
close association with Pantropical spotted dolphins in our
waters.
Spinner dolphins are taken in high numbers as bycatch in
purse-seine, gillnet, and trawl fisheries. Annual mortality
of hundreds of spinner dolphins have been reported in India,
and annual mortality in the thousands have been reported in
Sri Lanka. Direct kills occur in several areas, including
Sri Lanka and the Philippines and Indonesia. Spinner
dolphins are not believed to be facing critical threats in
pelagic waters of Bangladesh, but little is known about
interactions of these animals with fisheries in the
Swatch-of-No-Ground. |
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Bryde's
whales
Balaenoptera edeni/brydei
Local name - Timi
Bryde's whales are slim, streamlined, fast swimming and have
comparatively little blubber. The Bryde's whale has three
prominent bony ridges running from the tip of the snout to
the blowholes. There body is bluish-gray with white on the
underside. The pectoral fins are relatively short and
pointed at the tips, the dorsal fin is curved. Bryde's
whales have 250 to 350 baleen plates on each side of their
jaw, which are about 42 cm (16 1/2 inches) long. Some of the
baleen plates in the front of the mouth are white, while the
rest of the plates are black.
The taxonomy and fine-scale distribution of Bryde's whales
are uncertain. The large-form of Bryde's whale has a maximum
length of 14.6m males and 15.6m in females and does not
become sexually mature until it reaches at least 11.2m. This
form occurs worldwide in tropical and warm temperate waters.
The small form of Bryde's whale can attain sexual maturity
at a length of 9.0m and rarely grows larger than 11.5m.
Bryde's whales are not known to undergo long-range seasonal
migrations and high productivity in the Swatch-of-No-Ground
may support a resident population of this species. During
2004-2008, we made over 150 sightings of baleen whales of
which most were confirmed to be Bryde's whales (probably the
large form). Bryde's whales are not believed to be facing
critical threats in pelagic waters of Bangladesh.
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BANGLADESH_GLOBAL HOTSPOT FOR CETACEAN DIVERSITY_PANCD