Systematic position
Phylum CHORDATA Haeckel, 1874
Class MAMMALIA Linnaeus, 1758
Order ARTIODACTYLA Owen, 1848
Infraorder CETACEA Brisson, 1762
Family BALAENOPTERIDAE Gray 1864
Genus Balaenoptera Lacépède, 1804
Balaenoptera musculus Linnaeus, 1758 (Fig. 2)
Materials examined
Single female individual, stranded at Mandarmani beach, details measurements as mentioned in materials and methods section.
Description
Body slender and streamlined, head broad and U-shaped when viewed from above and relatively flat when viewed from side. Along the centre of the rostrum, there is a single prominent ridge, which ends in an impressive splash guard around the blowholes and another two ridges of less prominent are present in either side of prominent ridges (Figure. 2c). The flippers are long and pointed, and the dorsal fin is relatively small, variably shaped, and placed about three quarters of the way back from the snout tip. The board flukes have a relatively straight trailing edge and a prominent notch. The bluish grey dorsally and lighter underneath. The head is uniformly blue, but the back and sides are mottled. On the throat, there are 52 long pleats (some are fused) extending to near navel. Baleen plates not examined. The blow is tall and slender. The present report of the carcass of an approximately 40 ft female blue whale was washed ashore at Mandarmani Beach, Purba Medinipur District, West Bengal, India (21o39.850’N; 087o38.283’E) on June 29, 2020 (Table 1). The, blue whale and other cetaceans have been recorded in the recent year by Swatch of No Ground (SoNG), a proposed trans boundary Marine Protected Area in the Northern Bay of Bengal in EEZ of India and Bangladesh (Datta and Choudhury 2018), closed at current location. According to the IUCN Red List, the species is in the endangered category of IUCN red list (IUCN 2022). All blue whale are protected under Schedule I of the Wildlife Protection Act, 1972. Stranding of this species occurring after 2018 but not yet reported in the literature were included in this analysis if the specimen had been examined personally by one of the present authors and authenticated as being blue whale.
Table 1
Previous sightings and stranding of blue whale Balaenoptera musculus along the Indian coast (1874–2020).
S. No. | Month/Year | Location | Length (m) | Sex | Conditions | Sources |
1. | 1874 | Mangalore (Skeleton in Madras Museum) confirmed in Gibson-Hill (1950) | 14.4 m (48 ft) | NA | Dead | Moses (1947) |
2. | 1890 | Bay of Bengal & Malabar coast | NA | NA | Stranded | Blanford (1891) |
3. | 1901 | Rajakamangalam, 5 miles south of Muttum lighthouse between Colachel and Cape Comorin (present day Kanyakumari) | 5.56 m | NA | Travancore Museum | Pillay (1926) and James & Soundararajan (1979) |
4. | March 1905 | Gujarat | NA | NA | Stranded | Pillay(1926) |
5. | November 1906 | Thane (Maharashtra) | 13.6 | NA | | Millard(1947) |
6. | January 1911 | Viziadrug, Ratnagiri District | NA | NA | Stranded | Kinnear (1915) |
7. | December 1914 | Dhabool, 155 km south of Bombay | 12.5 | Male | Stranded | Prater (1915) |
8. | November 1927 | Cherai, Cochin, Kerala | 28.2 | NA | Skeleton at St. Aloysius College, Mangalore, India | Moses (1947) |
9. | February 1934 | Jambudwip, West Bengal | NA | NA | Stranded | Jones (1953) |
10. | May 1934 | Colaba Reclamation, Mumbai | 15.8 or − 21.3 | NA | | McCann (1934) |
11. | March 1939 | Mulvel, Gujarat | 24.1 | F | Dead | Moses(1940) |
12. | March 1939 | Kathiawar, Gujarat | 23.7 | NA | | Moses (1947) |
13. | May 1951 | Bombay | 22.2 | NA | | Chari (1951) |
14. | December 1960 | Ganeshgarm, Gujarat | 23.8 | F | Dead | Kewalramani (1969); De Silva (1987) |
15. | December 1960 | Gujarat | 23.4 | NA | | James and Soundararajan (1979) |
16. | February 1963 | Magdalla Port, Gujarat | 20.28 | NA | Dead and decomposed | Daniel(1963) |
17. | May 1966 | Calicut, Kerala | NA | NA | Stranded | Venkataraman and Girijavallabhan (1966) |
10. | April 1969 | Tuticorin, Tamil Nadu | NA | NA | | Bensam et al. (1972) |
11. | December1976 | Uvari, Trichendur, Tamil Nadu | NA | NA | | Marichamy et al. (1984) |
12. | September 1983 | Erayumanthurai, Tamil Nadu | | | | Venkataramanujam et al. (1984) |
13. | September 1985 | Narakkal, Kochi, Kerala | | | | Nair & Jayaprakash (1987) |
14. | August 1988 | Kalumbhar Island, Gujarat | 8.38 | NA | Dead and stranded ashore | Tiwari & Varu (2001) |
15. | September 1988 | Paravana, near Calicut, Kerala | NA | NA | | Lal Mohan (1992) |
16. | May 1993 | Cochin | 26.0 | NA | | James et al. (1993) |
17. | May 1994 | Visakhapatnam, Andhra Pradesh | NA | NA | | Mohanraj et al. (1995) |
18. | November 1994 | Dhanuskodi, Rameshwaram, Tamil Nadu | NA | NA | | Lipton et al. (1995) |
19. | October 1995 | Valappad beach, Thrissur, Kerala | NA | NA | | Baby (1996) |
20. | July 1997 | Ganga creek, Gujarat | NA | NA | | Tiwari & Varu (2001) |
21. | December 2001 | Guijerbettu, Udupi, Karnataka | NA | NA | | Anoop et al. (2004) |
22. | September 2005 | Gujarat | 22.5 | NA | Washed ashore | www.marinemammal.in |
23. | July 2006 | Kundugal, Mandapam, Tamil Nadu | NA | NA | | Afsal et al. (2008) |
24. | July 2016 | Gujarat | 13.2 | NA | Washed ashore | www.marinemammal.in |
25. | September 2017 | Una, Gujarat | 9.14 | NA | Live stranding | https://timesofindia.indiatimes.com/city/ahmedabad/30-feet-blue-whale-rescued-off-una-coast/articleshow/60785894.cms |
26. | April 2018 | Okha, Gujarat | 19 approx | NA | Live sighting | Chandrasekar et al. (2020) |
27. 28. | June 2020 August 2020 | Mandarmani, West Bengal Valinokkam, Ramanathapuram, TN | 40 ft 50 ft | F NA | Stranded Stranded | Present study Under publication |
The sequence obtained from B. musculus has accession number OM665387 and is 648 base pairs. The recently studied whale species B. musculus from West Bengal coast is compared with the related close sequences of GenBank blast result. The phylogenetic analysis and K2P distance confirm that the stranding record of whale species is B. musculus. The genetic data of recent study is compared with 27 sequences of all the species of genus Balaenoptera such as
B. musculus, B. brydei, B. omurai, B. edeni, B. physalus, B. borealis and B. ricei and additional two sequences of M. novaeangliae which are available in GenBank and BOLD. The recent
B. musculus differs genetically from other reported B. musculus with K2P distance 0 to 0.3%, but from all other comparative species sequences, it differs with K2P distance 6.4 to 9.9%. In the maximum likely hood tree B. musculus came under the same clade (Fig. 3).