Why in news?
Global stranding data shows blue and Bryde’s whales regularly wash up in Gujarat, but systematic recording has stopped.
UPSC Relevance – Prelims: Species in news – blue whale, Bryde’s whale, Arabian Sea humpback.
Cetaceans – Basics
Meaning: Cetaceans are fully aquatic mammals – whales, dolphins and porpoises. They breathe air through blowholes, are warm-blooded and give birth to live young.
Two groups of whales
| Basis | Baleen whales (Mysticeti) | Toothed whales (Odontoceti) |
| Feeding | Baleen plates filter krill, small fish and plankton | Teeth to catch fish, squid |
| Blowholes | Two | One |
| Echolocation | Absent; use low-frequency songs | Present |
| Examples in India | Blue, Bryde’s, humpback, fin, sei, minke, Omura’s whale | Sperm whale, killer whale, pilot whales, false killer whale, all dolphins and porpoises |
Marine Stranding
- A stranding, also called beaching happens when a marine animal—such as a whale, dolphin, porpoise, seal, or sea turtle—gets stuck on land or in water too shallow to return to the sea.
- Natural causes: Disease, old age, injury, getting lost in shallow, gently sloping coasts like the Gulf of Khambhat.
- Human causes: Ship strikes, entanglement in fishing nets, naval sonar and seismic surveys, plastic ingestion and chemical pollution.
- Of about 470 blue whale strandings recorded worldwide, India accounts for about one in seven; nearly three-quarters of these are on the west coast.
- Gujarat has 15 blue whale strandings on record, 14 of them in the 20th century, mostly in the Gulf of Khambhat and near Surat. After 2000, only one has been recorded. Whales kept coming; recording stopped.
- Fishers of Mandvi and Porbandar see whales from October to April and call baleen whales ‘Maccha Raja’ (king of all fish).
Blue Whale – Key Facts
- Scientific name: Balaenoptera musculus. The Northern Indian Ocean population is often treated as a separate subspecies (B. m. indica).
- Size: Largest animal ever known to have lived – up to about 30 metres long and over 150 tonnes. Its heart is roughly the size of a small car.
- Diet: Baleen whale; feeds mainly on krill, eating up to about 4 tonnes a day.
- Voice: Among the loudest animals on Earth; low-frequency calls can travel hundreds of kilometres under water.
- In India: Seen and stranded along the west coast (Gujarat, Maharashtra, Goa, Kerala), and around Sri Lanka and the Lakshadweep sea. Upwelling in the Arabian Sea during monsoon supports its food.
- Threats: History of commercial whaling, ship strikes, ocean noise, entanglement in fishing nets and climate change affecting krill.
- Status: IUCN – Endangered; CITES – Appendix I; WPA 1972 – Schedule I; CMS – Appendix I.
Other Whales Found in India
- Bryde’s whale (Balaenoptera edeni): Most commonly stranded baleen whale on Gujarat coast recently. Lives in warm tropical waters, does not make long migrations. Called ‘Machchh’ locally.
- Arabian Sea humpback whale (Megaptera novaeangliae): Most remarkable: unlike other humpbacks, which make the longest migration of any mammal, this group stays in the Arabian Sea all year. Genetically isolated for about 70,000 years. Only around 100 remain. Songs recorded off Goa, Karnataka and Maharashtra. Globally the humpback is Least Concern, but this subpopulation is Endangered.
- Sperm whale (Physeter macrocephalus): Largest toothed whale and predator; dives very deep to hunt squid. Produces ambergris, whose trade is banned in India.
- Short-finned pilot whale: Known for mass strandings. Over 100 stranded at Manapad beach, Thoothukudi (Tamil Nadu) in January 2016.
- False killer whale: In 2021, Karnataka recorded its first stranding of this species.
Practice MCQ
Q1. Consider the following pairs:
| Species | IUCN Red List status |
| 1. Blue whale | Endangered |
| 2. Bryde’s whale | Critically Endangered |
| 3. Sperm whale | Vulnerable |
| 4. Ganges river dolphin | Endangered |
How many of the pairs given above are correctly matched?
(a) Only one (b) Only two (c) Only three (d) All four
Answer: (c). Pair 2 is incorrect: Bryde’s whale is listed as Least Concern.
Q2. Consider the following statements:
1. The humpback whales of the Arabian Sea undertake long annual migrations to polar feeding grounds.
2. The blue whale is a toothed whale that hunts using echolocation.
3. All cetaceans found in India are listed in Schedule I of the Wildlife (Protection) Act, 1972.
How many of the statements given above are correct?
(a) Only one (b) Only two (c) All three (d) None
Answer: (a). Statement 1 is incorrect: Arabian Sea humpbacks are non-migratory and stay in the region all year. Statement 2 is incorrect: the blue whale is a baleen whale that filter-feeds on krill.
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