OBSERVATIONS ON THE BEHAVIOUR AND OTHER
BIOLOGICAL ASPECTS OF THE GANGES SUSU,
PLATANISTA GANGETICA
A.K.M. AMINUL HAQUE
Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh, Bangladesh

MASAHAR U NISHIWAKI
University of the Ryukyus, Naha, Okinawa

TOSHIO KASUYA
Ocean Research Institute, University of Tokyo, TokyoANDTERVO TOBAYAMA
Kamogawa Sea World, Awa-gun, Chiba

ABSTRACT

Observations on the behaviour of the Ganges susu, Platanista gangetica(Roxburgh, 1801 ), indicated that these animals frequent the confluence of asmaller stream with the main river, even with over-flooded banks, for food
fishes. The most satisfactory method so far tried for capture of these animals
was the use of' jagatberh '. With a little care these could be easily transported over long distances. Though they are known to be side-swimming, theGanges susu cruised in normal fish-like movement with the body in normal,
upright position. Rate of breathing showed individual and diurnal variations,the rate being more for younger specimens, and again during day-time. One
susu was seen chasing a big fish at a tremendous speed, another attacked agoose, and a third one attacked a fish caught in the hook and thereby itself got
caught in a locked-jaw condition. Two others reportedly were seen in theact of mating about an hour after sunset in August 1959. Parturition in theseanimals appears to occur around May, with another peak possibly aroundDecember.

INTRODUCTION

Thirteen live specimens of the Ganges susu, Platanista gangetica (Roxburgh, 1801),
collected at different times from the Brahmaputra-Jamuna-Meghna river-systems
during the period from January 1970 to May 1973 were each maintained for atime in ornamental pool, civil-work ponds, and/or in portable swimming pool in
the Agricultural University Campus at Mymensingh, Bangladesh. These wereamong a total of 44 specimens collected and studied during investigations on theSci. Rep. Whales Res. Inst.,
No. 29, 1977, 87-94.

88

HAQUE, NISHIWAKI, KASUYA AND TOBAYAMA

biology of the Ganges susu. Various aspects of their behaviour during captivity
in these small, artificial waterbodies as well as on land and in the river werestudied.
METHOD OF CAPTURE
The Ganges susu were found to avoid fast-moving boats, and seemed to be able tosense the presence of nets set in the vicinity. Various methods were tried for capture of these animals. The most satisfactory method was, however, found to be
the use of a special type of seine-net, locally called 'jagatberh' used for catching
bigger carps and other fishes in the river when the water-level was low. A row ofsuch nets mounted on specially constructed rafts is placed across the river at two
points each usually several kilometers apart. Dolphins are found to frequent theconfluence of a smaller stream with the main river evidently for food-fishes (Kasuya and Aminul Haque, 1972). This was true even with over-flooded bank of theriver. If the two components of the jagatberh were placed in the river enclosing
such confluences, chances are that several specimens of dolphin would be rounded
up towards the end of the jagatberh operation. Care has to be taken to remove
the dolphins from the net as quickly as possible, as otherwise the dolphins may getentangled in the net, and get drowned.
Harpooning may be possible at the confluence of two streams frequented bydolphins, but this was not tried.
HANDLING
On land the dolphins were relatively calm, showing not much of visible distress.
When picked up, they would struggle, within manageable limits, trying to wriggle
out of hands. An interesting thing noted in a number of cases was that supported
on one hand placed just below the throat-region, the dolphins became calm andstill, stopping all strugglings. This was most pronounced in a calf about three
weeks old (No. 33, 76 cm, ~) that had been held in the swimming pool for 30days since 8 June 1970.
TRANSPORTATION
Transportation on land from the place of capture to Mymensingh was easily doneon a stretcher by two men, or on the lap by one man-longer distances being covered by rickshaws or trains with the animal left on the footboard or on the floor of
the train compartment, as the case may be. The animal was loosely wrapped up
with a length of rug leaving the blow-hole uncovered, the rug being kept wet byoccasional sprinkling of water so as to keep the skin moist and cool. When released in artificial waterbodies, like ponds, the animals recovered in no time, without any apparent ill-effects. The breathing rate stabilised slowly from little under
500 times per hour on land to about 65 times per hour in water.
Sci. Rep. Whales Res. Inst.,
No. 29, 1977.

BEHAVIOUR OF GANGES SUSU89

For really long distances covering several thousand kilometers (MymensinghDacca, 200 km by truck; Dacca-Bangkok-Manila-Tokyo, 5,000 km by plane; andin some cases, Tokyo-Kamogawa, 100 km by truck again) the animals, duly wrapped up with wet rug, were placed in wooden crates of suitable size lined with
polyethylene sheets and with 7-10 cm of water added. The animals stood the long
journeys, in some cases, of about 21 continuous hours, surprisingly well, and recovered from the shock of the unusual journey fairly quickly.
SWIMMING

In confined, shallow waters-for example, in ornamental pool (865 X 360 X
45 cm deep, with a fountain-base, 65x65 cm, in the middle), small pond (960X
725 X 80 cm deep), or swimming pool (450 cm dia. X 105 cm deep )-the dolphinsswam on one side nodding the head continuously in ' yes ' motion. One remarkable thing noted is that, of the thirteen specimens observed in shallow waters, all
except one swam in anti-clockwise direction, that is, on the right side, while only
one swam in clockwise direction or on the left side. This 'right- or 'left-handedness' may well be controlled genetically, so that occasional individuals with left
side-swimming may not be unexpected.
The Indus susu, P. minor Owen, 1853, has also been reported to be a sideswimming cetacean with individuals moving either clockwise or anti-clockwise(Herald et al., 1969). We are, however, inclined to believe that side-swimming in
the Ganges susu is only one aspect of its swimming behaviour under specific environmental conditions-like small, confined area and depth of the waterbody. Further, contrary to popular explanation for side-swimming, this may not have anything to do with food-seeking or food-catching.
On one occasion, as described elsewhere in this paper (vide infra), a specimenof the Ganges susu was seen chasing a big fish in the river at a tremendous speed.
This was a normal, fish-like swimming movement, with the body in normal, upright position.
TERRITORY FORMING
Ganges susu are non-gregarious creatures (Kasuya and Aminul Haque, 1972),
although occasional two-most probably mother and calf as suggested by sizedifference-have been seen swimming up or down the river.
Two specimens (No. 31, 138 cm, ~; and No. 32, 123 cm, 6) maintained ina pond during the period from 17 May to 21 August 1970, established themselvesin two mutually exclusive areas in the pond, never crossing-as far as could beascertained from their surfacings-into each other's territory. Also, they were observed never fighting with, or chasing, each other in the pond. These observations
were true of two other specimens (No. 22, 188 cm, 6; No. 24, 166 cm, 6) similarly maintained in another pond.
Sci. Rep. Whales Res. Inst.,
No. 29, 1977.

HAQUE, NISHIWAKI, KASUYA AND TOBAYAMA

90

BREATHING RATE

The ' blowing ' of the Ganges susu is a composite act-exhalation, quickly followed
by inhalation-both done so quickly within a fraction of a second that the twosounds appear to be of one single action. It is interesting to note, however, thaton one occasion on 15 May 1973 a specimen (No. 38, 91 cm, d') placed on a tablein the Laboratory was found to have missed inhalation in one blowing, which was
followed after only two seconds by another blowing, this time only inhalation taking place, so that for all practical purposes there were two separate blowings forexhalation and inhalation with a two-second interval between the two.
There were individual and diurnal variations in the rates of breathing of theseanimals. Record of breathing as kept for different specimens maintained in artificial waterbodies as well as on land has been summarised in Table 1 below. It
may be noted from the Table that the minimum breathing rates for any individuals
TABLE 1.

RATES OF BREATHING OF SEVEN SPECIMENS OF PLATANISTAGANGETICA UNDER DIFFERENT CONDITIONS(Unless otherwise stated, breathing rate was recorded for 60 continuous
minutes each time within the hours mentioned.)
Rate of breathing per hour
On landSpecimen
No.

Sex

Size
(cm)

22

cJ

188

24
31

cJ

166
138

~

123

32

33
36
38

~
~

cJ

76
130.5
91.0

Date

27-4-'70
8-5- 170
8-5-'70
15-5-'70
16-5-'70
17-5-'70
26-5-'70
21-8-'70
15-5-'70
16-5-'70
17-5-'70
26-5-'70
21-8-'70
9/10-6-'70
24-6-'70
30-9-'70
15-5-'73

0600
to
1000
hrs.

1200
to
1600
hrs.

492bJ

In water
1900
to
1830
hrs.

0600
to
1000
hrs.

1200
to
1600
hrs.

1700
to
1830
hrs.

53
43
58
121/2al127 /2al52
42
54
129/2al

58

0000
to
0100
hrs.

348bJ
64
40
121/2•l127/2aJ

444bl

129/2•)

204bl
67
88
88
96

68
92

106C)
40
58

156d>

•> Combined data for two specimens (Nos. 31 & 32.)b> Breathing recorded for 15 minutes (and multiplied by 4) while being transported in a railway cornpartment.
cJ Breathing recorded one day after capture.
d> Breathing recorded for 10 minutes (and multiplied by 6) in the laboratory half an hour after arrivalby road.
Sci. Rep. Whales Res. Inst.,

No. 29, 1977.

BEHAVIOUR OF GANGES SUSU

91

were recorded for two specimens (Nos. 33 and 36) at nights, and the same could
indicate their hours of sleeping. Two other specimens (Nos. 31 and 32) also recorded low breathing rates (on 21 August 1970) when they had in fact become
very much emaciated due apparently to starvation. One of these latter two specimens (No. 31) died some 10 hours after the minimum breathing rate of 40 per
hour had been recorded, and the other specimen was sacrificed the next day.
During transportation, the breathing rate of these animals was, for obvious
reasons, significantly higher than under acclimatised state in water.
FEEDING HABITS(a) Acceptance or rejection of food: While specimens of the Ganges susu readily accepted food (small fishes) from the handler in the ornamental pool and in theoceanarium, those kept in the pond did not accept food offered to them, nor did
they seem to take any food from the pond which had previously been stocked withan assortment of fishes of various sizes. Specimens left in ponds seemed to haveslowly starved to death as the general emaciated state of health and post-mortem
examination of the stomach would indicate.
(b) Attack on a goose: Specimen No. 22, while in a pond, once bit the neck of
a domestic goose, Anser cygnopsis cygnoides, while the latter was, in its characteristicmanner, probing the pond-bottom for food. The dolphin, however, loosened its
grip and the goose managed to come out of the water. The injured goose wasthen slaughtered, and on examination the neck and part of head were found tohave rows of tooth-marks on both the sides, establishing that the goose had reallybeen bitten by the dolphin (Plate I, Fig. 1).
(c) Dolphin caught in a hook: An unusual case of a dolphin getting caught ina hook was brought to light on 28 September 1970. On the preceding night twoanglers had placed a series of hooks each hanging from a bamboo rod, and fixednear the bank of the river. There were live baits (small fish or frog) hooked to theline, the hooks just touching the surface of water. This was a common local method of catching such predatory fishes as freshwater shark (Wallago attu, a kind of
Teleostomi), featherback (Notopterus chitala) and snakeheads (Channa striatus and C.
marulius).
At about 0200 hours, local time, the anglers were attracted by violent splashing sounds from the direction of one of the hooks. They took this to be caused by
an extra-large freshwater shark, and hauled it up with a push-net. They were,
however, shocked to see a Ganges susu instead, and decided to present the
curious specimen to the Faculty of Fisheries across the river. When the specimen
was brought to us early in the morning, we were bewildered to understand thecircumstances under which the dolphin got caught in the hook. As stated above,
the hook had a live bait of a frog or small fish, which lured to the hook a 36 cm
freshwater shark, which, in its turn, attracted the dolphin. On examination thehook at the end of a length of string, was found deep into the oesophagus of thefish, which, in its turn got caught in the jaws of the mammal, the hook nowhere
Sci. Rep. Whales Res. Inst.,
No. 29, 1977.

HAQUE, NISHIWAKI, KASUYA AND TOBAYAMA

92

even touching the jaws of the latter. Apparently, the dolphin found itself in a'locked-jaw ' condition, in which condition it was still fixed to the fish in the latter's abdomen and tail region that bore on the dorsal side distinct tooth-marks ofthe dolphin (Plate I, Figs. 2-4). The 130.5 cm dolphin (No. 36) was still alive,
and after being maintained for 9 days in a swimming pool, was transferred to
Kamogawa Sea World in Japan to start a new life in the oceanarium there.
CHASING A BIG FISH

On 17 October 1969, when the river old Brahmaputra was in half spate, a big (approximately 45 cm) carp, Labeo rohita, was seen being chased by a Ganges susu
close to the surface of the water, to almost where one of the present authors withseveral friends had been standing near the edge of the water. Both the fish andthe mammal were cruising at tremendous speeds, the latter continuing to chasethe former to some 10 meters beyond the amazed on-lookers after which they bothswam deeper down in water beyond sight.
MATING

Judging by the date of capture of very young, untoothed and teething calves, itappears safe to say that parturition in the Ganges susu in the river-system in Bangladesh takes place around May. According to Anderson (1878) parturition in
TABLE 2. PARTICULARS OF 13 YOUNG SPECIMENS OF GANGES SUSU,
PLATANISTA GANGETTCA, ALL LESS THAN 120 CM IN LENGTH
Specimen No.
Sex
at BAUat ORI

33

14
21

38

3
2
7
II
15
4
16
9
17

~
~

6

2
5
7
11
3
13

6
6
~

6
~

6

6
6
6

15
KS-76-5

6

~

Size
(cm)

Date ofcollection
or capture

27
67.4
76
91

100.5
105
llO
113
113
115
115
117
118
118

River*

Remarks

28- 8-67
8- 6-70
8- 7-70**
15- 5-73

M
B

FoetusHair follicles very prominent;
Teeth not erupted
Hair follicles prominent;
Only 10 or II teeth on eachside of the jaws erupted;
Curdy substance found in mouth?- 6-69?- 6-69

B
B
B
B

20-10-69
6- 1-70
26- 1-70
23- 8-69
26- 1-70
20-12-69
26- 1-70
13- 9-76

B

J
B

J
B
J
B

* River-names : M-Meghna; B-Brahmaputra; J-Jamuna** Date of taking second measurement.

Sci. Rep. Whales Res. Inst.,
No. 29, 1977.

BEHAVIOUR OF GANGES SUSU

93

the Ganges susu may occur in two seasons-between April and July, and November and December. Harrison (1972), however, believes that parturition inthis animal probably occurs in April, and he gives the length of neonates as 7075 cm. From details of 13 young specimens, all measuring less than 120 cm (Table2), it may reasonably be concluded that parturition in the Ganges susu takes
place around May. Whether a second season for parturition exists for this animalcannot be confirmed from available data. The capture of 5 of the 13 specimens
listed in the Table, all belonging to the same size-group (113-118 cm), in December-January, indicates that these were all born about the same time of the year.
Since the age of these individuals was estimated with dentinal growth layers as 1.0
year (Kasuya 1972), it seems possible to expect another parturition peak aroundDecember.
There is no reliable information to estimate the period of gestation in theGanges susu. Assuming that the period of gestation in these animals is 9 months(Anderson, op. cit.), mating would appear to take place around July/August. The
collection of a 27 cm foetus on 28 August 1967 at Chandpur (R. Meghna) would
lend support to this assumption.*
One first-hand report from a Professor, an M.A. in Bengali language, andhaving no biological background, describes an incident involving two dolphins(Prof. M.A. Nawaz, BAU; pers. comm.). It was about an hour after sunset on
14 August 1959. The gentleman, while crossing the river Burhiganga at Dacca on
board a small country-boat, was alarmed at violent splashings in the water of two
huge struggling creatures, locked in embrace, and rolling and almost shooting out
of water. Both the Professor and the boatman watched in horror this 'struggle'
that was apparently an act of mating of two dolphins. The boatman was, however, categorical that it was actually so.
ACKNOWLEDGMENT

The authors wish to thank the authorities at the Bangladesh Agricultural University, Mymensingh, Bangladesh, at the Ocean Research Institute, University ofTokyo, Japan, and at the Kamogawa Sea World, Chiba, Japan, for the generous
help and co-operation received at different times during the period of study reported in the present paper.

* Since the paper was sent to the press, a second foetus, 30 cm, has been collected on 13 October 1977
from the river Meghna.
Sci. Rep. Whales Res. Inst.,
No. 29, 1977.

94

HAQUE, NISHIWAKI, KASUYA AND TOBAYAMAREFERENCES
ANDERSON, J., 1878. Anatomical and zoological researches: comprising an account of the zoological result of the two
expeditions to Western Yunnan in 1868 and 1875, and a monograph of the two cetacean genera Platanista and Orcella, vol. 1. B. Quaritch, London, 564 p.
HARRISON, R.J., 1972. Reproduction and reproductive organs in Platanista indi and Platanista gangetica.
In: Investigatians on Centacea Vol. IV, ed. G. Pilleri, 71-82, Berne.
HERALD, E. S., R. L. BROWNELL, Jr., F. L. FRYE, E . .J. MORRIS, W. E. EVANS, and A. B. ScoTT, 1969. Blind
river dolphin: First side-swimming cetacean. Science, 166: 1408 :1410.
KAsUYA, T., 1972. Some information on the growth of the Ganges dolphin with a comment on the Indus
dolphin. Sci. Rep. Whales Res. Inst., 24: 87-108.
KASUYA, T., and A.K.M. AMINUL HAQ,UE, 1972. Some information on distribution and seasonal movementof the Ganges dolphin. Sci. Rep. Whales Res. Inst., 24: 109-115.

EXPLANATION OF PLATE
PLATE I
Fig. 1. Head of a goose with rows of tooth-marks of a Ganges susu.
Figs. 2-4. Specimen of a freshwater shark ( Wallago attu) with tooth-marks of aGanges susu on its body.

Sci. Rep. Whales Res. Inst.,

No. 29, 1977.

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