Sperm
Whale Physeter macrocephalus stranded at Devbagh beach,
Karwar, western coast of India
U.G. Naik 1, J.L.
Rathod 2 & S.B. Haragi 3
1,2,3 Department of Marine Biology,
Karnatak University Post Graduate Centre, Kodibag, Karwar, Uttara Kannada,
Karnataka 581303, India
Email: 1 ugnaik66@yahoo.co.in,2 jagannathrathod9@gmail.com, 3 shivu398@yahoo.com
Date of publication (online): 26 November 2010
Date of publication (print): 26 November 2010
ISSN 0974-7907 (online) | 0974-7893 (print)
Editor: Luke Rendell
Manuscript details:
Ms
# o2406
Received
19 February 2010
Final
received 06 August 2010
Finally
accepted 11 November 2010
Citation: Naik, U.G., J.L. Rathod & S.B. Haragi (2010). Sperm Whale Physeter macrocephalus stranded at Devbagh beach, Karwar,
western coast of India. Journal of Threatened Taxa 2(12): 1338-1341.
Copyright: © U.G. Naik, J.L. Rathod & S.B. Haragi 2010. Creative Commons Attribution 3.0 Unported
License. JoTT allows unrestricted use of this article in any medium for
non-profit purposes, reproduction and distribution by providing adequate credit
to the authors and the source of publication.
For figures, images, tables -- click here
Karwar Bay is located in the
Arabian Sea on the central western coast of India (14048’05”N &
74007’48”E) (Fig. 1), and is known for its rich bio-resources such
as crustaceans, mollusks, and fin fishes. This section of the coast is popularly
known as the ‘mackerel coast’. Rich marine resources like squids, prawns and
other invertebrate animals support a very good fishery in this area. In fact, this area is a very good
feeding ground for many pelagic fishes as well as marine mammals. It is a breedingand feeding ground for dolphins, porpoises and whales all of which visit this
area seasonally.
The cetaceans are a diverse group
with fossil evidence dating back more than 50 million years. All living families of toothed whales
evolved 5-25 million years ago (Joseph & Velerie 2005). The Sperm Whale belongs to the sub
order Odontoceti, family Physeteridae, and is cosmopolitan in
distribution. The species name
comes from the presence of spermaceti in its head. It has a large head (one-third of its body length), and the
S-shaped blowhole is located very close to the front of the head (Whitehead
2002) on the left
side. This gives rise to a
distinctive bushy, forward-angled blow.
It is a sexually dimorphic
cetacean, although both sexes are the same size at birth (Shirihai
& Jarrett 2006). Adult male Sperm Whales grow up to 67ft
(20.5m) and weigh up to 57,000kg (Whitehead 2002). As they grow, mature males typically attain
sizes 30 to 50 % bigger and three times as massive as females. Females have longer and more prominent
genital slit which encompasses the closer spaced genital and anal openings and
is flanked by small slits on each side containing nipples.
Materials and Methods: On 17 September 2009, at 1730hr, a
female Sperm Whale was stranded at Devbagh beach (14050’34.97”N & 74006’47.87”E) about 2km away from
the Karwar coast (Fig. 1 & Image 1). Devbagh beach is located about 1.5km northwest of Karwar beach. This beach is covered with casuarina
plantations (Equisetifolia sp.) and areas of Ipomea pes-carpe, a sand dune plant. The beach is connected to the mouth of the Kali Estuary in the south and
is a known turtle breeding ground. Due to the onset of darkness, morphometric studies could not be made at
the time of initial discovery and hence the morphometric study of the stranded
sperm whale was done the next morning (Table 2). The tidal amplitude was 0.51m at 1548 hr on 17 September
2009 and 0.30m on 18 September 2009 at 1430hr. The measurements were taken based on Joseph & Velerie
(2005).
Karwar area air, water temperature
and humidity were obtained from the Karwar Meteorological Department. Tidal amplitude data for the study area
were procured from the Department of Port, Karwar and are presented in Table
1. Prey catch statistics of Karwar
area were obtained from the Karnataka State Fisheries Department, Karwar, India
and presented in Table 3.
Results: The mammal was first sighted by
fisher folk of the Goa coast (Polem beach), about 8km north of Karwar bay and
at that time was active and very close to the shore (2km). The next day it was sighted at Karwar
bay (Devbagh beach) in the evening, and due to the shallow depth was observed
to be struggling to go back to the sea. Rescue attempts were made by fishermen and local
people along with scientific personnel of the Department of Marine Biology,
Post Graduate Centre of Karnatak University, but they did not succeed
before the onset of darkness. The
next morning the mammal was found dead, lying very close to the shore. There were no physical injuries apparent
on the animal’s body. Morphological studies were carried out and details are
given in Table 2 and Figure 2.
Discussion & Conclusions: Mortality such as observed here may be due to injury, illness, contaminants, parasites,
disease and starvation or anthropogenic causes. The observed stranding correlates with an unusually low
tidal amplitude (leading to shallower than normal waters)
which may have been a factor in the stranding. This is initially supported by to the lack of external body
injury. As this area is not a
known breeding ground of this species, the appearance of this sperm whale in
this region is probably due to foraging, as squids are the main dietary
components of this whale. This
might have attracted the whale to these rich waters. The catch statistics of prey species in this region support
this interpretation. It was also
observed that the previous day and on that day, there was a high catch of
squids, prawns, silver pomfrets and small fishes in the particular area, as
reported by indigenous fishers. A
comparatively high catch of squid, the main diet of the Sperm Whale, was noted
in and around Karwar waters during August and September of 2009. In the month of August, the squid catch
was 16.0 metric tonnes whereas during September it was 48.0 metric tonnes.
The stranded animal was identified
as a female Sperm Whale Physeter macrocephalus (Images 2-6). Later,
the whale was buried in the beach (Image 7) to preserve its skeleton for
further studies. Physeter macrocephalus is a Vulnerablemammal (IUCN 2008) and the U.S. has listed it as an endangered species.
According to Joseph & Velerie
(2005), saving a live-stranded animal is not always possible, but here an attempt
was made, which although it failed, provided valuable insight for rescue
operations in future.
References
Joseph, R. G. & J.L.
Velerie (2005). Marine Mammals Ashore - A Field Guide for Strandings. 2nd Edition. National Aquarium, Baltimore, 371pp.
Perrin, W.F. (1975). Bulletin of
Scripps Institute of Oceanography. 21: 3-12. American Cetacean Society
Fact Sheet, ACS National H.Q. P.O. Box 1391, San Pedro, CA 90733, USA.
Shirihai, H.S. & B. Jarrett (2006). Whales Dolphins and Other Marine Mammals of the World.
Princeton University Press, Princeton, New Jersey, pp. 21-24.
Whitehead, H. (2002). Sperm Whale Physeter macrocephalus. pp. 1165–1172, In: Perrin, W., B. Würsig &
J. Thewissen (eds.). Encyclopedia of Marine
Mammals. Academic Press,
San Diego, CA.