Kogia breviceps (de Blainville, 1838)

Russell A. Mittermeier & Don E. Wilson, 2014, Kogiidae, Handbook of the Mammals of the World – Volume 4 Sea Mammals, Barcelona: Lynx Edicions, pp. 318-325 : 324-325

1. Pygmy Sperm Whale Kogia breviceps

French: Cachalot pygmée / German: Zwergpottwal / Spanish: Cachalote pigmeo

Other common names: Lesser Cachalot, Lesser Sperm Whale, Short-headed Sperm Whale

Taxonomy. Physeter breviceps de Blainville, 1838 ,

South Africa, Western Cape Province, “rapportée des mers du cap de Bonne-Espérance” (= Cape of Good Hope).

This species is monotypic.

Distribution. Cosmopolitan in temperate and tropical waters of the Atlantic, Pacific, and Indian oceans; concentrations of stranding records occur along E USA, South Africa, and New Zealand and to a lesser degree on French and Spanish coasts; precise at-sea distribution is unknown.

Descriptive notes. Total length 270-420 cm; weight 342-680 kg. Condylobasal length of the skull of the Pygmy Sperm Whale is 39.1-46.9 cm. Juveniles ofshorter total length and body weight than the minima referenced here also strand. The Pygmy Sperm Whale is variable in color, but it is generally blackish-brown dorsally shading to cream on belly. Relative position of foramen magnum near midpoint ofskull height in the Pygmy Sperm Whale is well below midpoint ofskull height in the Dwarf Sperm Whale (K. sima); this characteristic has been reported to be diagnostic, but overlap in this feature has been noted in individuals from South African waters. Other diagnostic cranial characteristics include sagittal septum (broad, 2.3-8 cm, with gradually sloping sides in the Pygmy Sperm Whale and narrow, 6-14 mm, with near vertical sides in the Dwarfsperm Whale) and degree ofslope from dorsal rim ofcranial fossae (gradual in the Pygmy Sperm Whale and steep in the Dwarf Sperm Whale). Height ofthe dorsal fin is less than 5% of body length in the Pygmy Sperm Whale and is one of the principal external features used to separate it from the Dwarf Sperm Whale. In the Pygmy Sperm Whale, the distance between the snout and anterior insertion ofthe dorsal fin is greater than 50% oftotal body length. Lowerjaw of the Pygmy Sperm Whale has 12-16 (rarely 10-11) teeth on each side and generally none in upper jaw.

Habitat. Deep water, typically seaward of the continental shelf. The Pygmy Sperm Whale is the most common species to strand on New Zealand and the second-most commonly stranded cetacean on the US Florida coast. In the Gulf of Mexico, the Pygmy Sperm Whale is sighted in waters with depths of 400-3500 m, but it is most frequently seen in waters of 400-1000 m. It also is seen more frequently in temperate waters than the Dwarf Sperm Whale.

Food and Feeding. Stomach contents demonstrate that the Pygmy Sperm Whalefeeds on a wide variety of pelagic squid species, often eating immature squid. Fish and crustaceans are also consumed and appear to be more important in the diet of the Pygmy Sperm Whale than in the Dwarf Sperm Whale. Rarely, mollusks and colonial tunicates such as salps are reported in stomach contents. Pygmy Sperm Whales mainly eat histioteuthidid, cranchiid, lycotethid, and enoploteuthid cephalopods, including Histioteuthis miranda (New Zealand), H. reversa (Spain and Scotland), Stigmatoteuthis hoylei (Hawaii), Teuthowenia pellucida (New Zealand), Taonius pavo (Hawaii), Lycoteuthis diadema (South Africa), and Enoploteuthis chunu (Taiwan). Feeding at depths of up to 500 m has been suggested for juvenile Pygmy Sperm Whales and at 650-1100 m for adults. It has also been proposed that Pygmy Sperm Whales feed at shallower depths, following daily movements of prey or perhaps even feeding primarily at night when cephalopods are closest to the sea surface. Nevertheless, three of the ten most abundant cephalopod prey species in stomachs of Pygmy Sperm Whales stranded on Hawaii do not undergo daily migrations, suggesting that at least part of the time is spent foraging at depths of 600-1200 m. Breeding. Off South Africa, male Pygmy Sperm Whales reach sexual maturity at c.240 cm in length and 2-5-5 years of age and females at ¢.260 cm and five years old. Length and weight at birth are estimated at ¢.120 cm and c¢.53 kg, respectively.

Activity patterns. There is no specific information for this species, but a rehabilitated juvenile Pygmy Sperm Whale that was tracked made repeated night time dives that averaged more than eight minutes.

Movements, Home range and Social organization. The Pygmy Sperm Whale is assumed to be largely solitary. Atsea group size is 1-6 individuals, and a mean group size of 1-2 individuals has been recorded in the Gulf of Mexico. Maximum number of individuals stranding simultaneously is three (one male and two females). Off South Africa, Pygmy Sperm Whales seem to strand more frequently in July-October (winter-spring). Strandings occur more often in October-March (autumn-winter) on coasts in the north-eastern Atlantic Ocean, and they peak in August-September (late summer—autumn) in the south-eastern USA. Strandings along coasts of the eastern USA may be associated with inshore and offshore movements of the Gulf Stream, with Pygmy Sperm Whales coming ashore when warm waters are farthest offshore. Elsewhere, strandings do not suggest seasonal changes in distribution of the Pygmy Sperm Whale, or that it is migratory. Nothing is known about social organization of the Pygmy Sperm Whale.

Status and Conservation. CITES Appendix II. Classified as Data Deficient on The [IUCN Red List. Nevertheless, the real conservation status of the Pygmy Sperm Whale is uncertain and may range from Least Concern to a more threatened category. There are no estimates of global abundance, although frequent strandings in some areas suggest the Pygmy Sperm Whale may not be as uncommon as sightings suggest. Population estimates from specific regions in 2003-2006 should be considered provisional, but they suggested 247 Pygmy Sperm Whales off the coasts of California, Oregon, and Washington (USA) and 7251 off Hawaii; collectively, there may be only 395 Pygmy Sperm Whales and Dwarf Sperm Whales in the western North Atlantic Ocean and 742 in the northern Gulf of Mexico. Current information is insufficient to evaluate population trends.

Bibliography. Baird et al. (1996), Barnes (1973), Beatson (2007), Bianucci (1997), Cardona-Maldonado & Mignucci-Giannoni (1999), Fitzgerald (2005), Hale (1947), Long (1991), McAlpine et al. (1997), Owen (1866), Piller (1986), Reeves, Stewart, Clapham & Powell (2002), Rice & Wolman (1990), Santos et al. (2006), Scott et al. (2001), Stamperet al. (2006), Taylor et al. (2008h), Thomas et al. (1990), West et al. (2009).

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Distribution. Cosmopolitan in temperate and tropical waters of the Atlantic, Pacific, and Indian oceans; concentrations of stranding records occur along E USA, South Africa, and New Zealand and to a lesser degree on French and Spanish coasts; precise at-sea distribution is unknown.