Opportunistic sighting of a Sperm Whale Physeter macrocephalus Linnaeus, 1758 in Lakshadweep Archipelago

The Sperm Whale Physeter macrocephalus is the world’s largest toothed whale and the only living species of the genus, Physeter. We report  an opportunistic sighting of a sperm whale with photographs from one of the recent protected areas (Pitti Islet) of Lakshadweep archipelago. 

ISSN 0974-7907 (Online); ISSN 0974-7893 (Print)  (Mittermeier & Wilson 2014). It is the world's largest toothed whale having the biggest brain of any animal species (Marino 2004). This species is characterised by a very large and rounded head which hold large quantities of a waxy substance known as spermaceti; the blowhole opens at angle from the left side of nasal passage; body colour is deep black to brownish-gray above with white markings around lips; instead of a dorsal fin, this species has distinct thick, low, and triangular humps (Jefferson et al. 1993;Menon 2014). It may live alone, or in small groups of 20-40 individuals or more in greater than 1,000 m deep oceans and undertake extensive migration (Taylor et al. 2019). Their distribution range is from Antarctic and cold-temperate waters (Northern hemisphere) to tropical waters (Mittermeier & Wilson 2014). In India, this species has been recorded all along the coastal states of Gujarat, Karnataka, Kerala, Tamil Nadu, Puducherry, Andhra Pradesh, Lakshadweep Islands, and Andaman & Nicobar Islands (Kumarran 2012; Marine Mammals of India database 2022).
Recently, the Government of India declared three protected areas in the Lakshadweep archipelago. Among these, Pitti Island (Pitti Islet) is the one where Zoological Survey of India conducted a marine faunal exploration under MoEFCC-ZSI in-house activity during February 2022. During the survey period, a single Sperm Whale was observed while partially breaching through the water surface on 7 February 2022 at 0853 h (Beaufort Sea state 1). It was recorded between Kavaratti and Pitti Island (10.653 0 N & 72.598 0 E). Based on the distinctive large rounded head (Image 1a), an angled bushy blow of water from the left side of its nose (Image 1b) and the thick and triangular hump on the back (Image 1c), the whale was confirmed as Physeter macrocephalus Linnaeus, 1758. However, the size of the whale and its behaviour except breaching could not be ascertained as it was J TT observed at a distance of about 500 m.
Although the Sperm Whale ranges worldwide, their record in Lakshadweep coasts is limited. From 1890 to 2018, there are 10 records of Sperm Whale reported from Kalpeni and Chetlat Islands of the Lakshadweep archipelago, of which eight records are strandings (James 1990;James & Panicker 1994;Pande et al. 2009). After 2009, only a stranding report was documented without locality information from Lakshadweep (a fisherman record) in 2018 (Marine Mammals of India database 2022). Here, we report an opportunistic sighting of a Sperm Whale from Pitti Island of Lakshadweep archipelago. Pitti Island lies within the Indian Ocean Cetacean Sanctuary (IOCS). Sperm Whales occur in the IOCS which is a potential feeding and calving ground (De Boer et al. 2003).
Besides the common threats from natural and anthropogenic impact, the illegal ambergris (a solid waxy substance that originates from the digestive system of Sperm Whale) trade is considered as a major threat to this species (Anonymous 2021(Anonymous , 2022Raveendran 2022). Due to rafting behavior at the surface between deep dives, it is also more vulnerable to vessel strikes (NOAA Fisheries 2022). Thus, this species is classified as 'Vulnerable' globally by the IUCN Red List of Threatened Species (2022)

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