The Pygmy sperm whale is one of the least know cetacean species, together with the dwarf sperm whale (Kogia simus), the only other species in the genus Kogia. They are very closely related and were recognised as separate species only 50 years ago. They are particularly difficult to distinguished however the position and size of their dorsal fin are some indicators to identify them.
Physical description and behaviour:
Pygmy sperm whales have stout and small bodies of around 2.7 to 3.8 m long. Their back is dark and slightly humped back and their dorsal fin small and recurved, which is proportionally smaller than that of dwarf sperm whales – usually under 8% of the snout to fin length. Their head is only one-sixth of the body length, is conical-shaped and becomes squarer with age. They do not have a beak. Their body is dark blue-grey on the back, outer margins of flippers and upper surface of tail flukes, lightening to pale grey on the flanks and dull white belly. Their skin can additionally have a wrinkled look. The flippers are rather long and are set far forward on the sides close to the head. They also have a hooked and low dorsal fin a little behind the centre of the back.
They are believed to feed on fish, crustaceans and squids (Beatson, 2007; Brentano & Petry, 2020).
They are very difficult to observe at sea except in extremely calm conditions. Little is thus known about their behaviour, apart from they surface rather slowly and may lay still for some time in calm seas.
Distribution and abundance:
The species is found worldwide in temperate, subtropical and tropical seas in both hemispheres. We know little about it and most information come from strandings, especially on the coasts of North America. They however seem to prefer more temperate waters than the dwarf sperm whale.
In the ASCOBANS Agreement Area, the majority of strandings happened in the Atlantic European coasts, namely in France, the United Kingdom, Ireland and one in the Netherlands in 1925. A few also occurred in Spain and Portugal although they are less common than in the previously mentioned countries. A few sightings have also been recorded in the British and Irish waters and in the Bay of Biscay.
IUCN Red List of Threatened Species™ Assessment
There has been an increase in strandings since the year 2000 in northern Europe, and a potential reason for it could be increased sea temperatures in the regions due to climate change. Indeed, pygmy sperm whales’ preys are adapted to a certain range of temperature and thus move higher up north. The whales then follow them, resulting in an increase in strandings as they would normally live offshore and be undetected. The numbers of strandings may then be a proxy for a distribution range shift or extension further north. This is however still a hypothesis and has not been confirmed yet.
|CMS Instruments||ASCOBANS, ACCOBAMS, Western African Aquatic Mammals, Pacific Islands Cetaceans|
|IUCN Status||Least concern|
No pictures for Kogia breviceps
|English||Pygmy Sperm Whale|
|Scientific name||Kogia breviceps|
|Additional notes||Updates have been made in August 2021 as per European Whales, Dolphins and Porpoises by Peter G. H. Evans (2020) unless stated otherwise.|