New Zealand Beaked Whale Stranding Reveals Genetic Separation of Species
A study recently published in Proceedings of the Royal Society B, has described a new species of beaked whale, Ramari's beaked whale (Mesoplodon eueu), thought to have separated from its closest relative some half a million years ago.
Ramari's beaked whales had previously been identified as True's beaked whales (Mesoplodon mirus), until a female specimen that washed ashore off the western coast of New Zealand's South Island in 2011. The animal, a pregnant, 5m-long female named 'Nihongore' by the local Ngāti Māhaki Māori tribesfolk, was sent for preservation to the New Zealand Te Papa Tongarewa Museum in Wellington, which today holds the complete skeletons of the whale and her unborn calf.
The researchers initially thought that the whale was the first True's beaked whale – populations of which are found in both the Northern Atlantic and Indian Oceans – to have been found in New Zealand's waters. Upon closer examination, the team realised that the shape of Nihongore's skull differed to that of the True's beaked whales previously found in the Southern Hemisphere, however, and subsequent testing revealed that the New Zealand specimen was genetically different to the other species.
The discovery of the new species was made by Māori whale expert Ramari Stewart – for whom the species is named – and marine biologist Dr Emma Carroll from the University of Auckland, in collaboration with an international team of over 30 scientists, including researchers from the Scottish Marine Animal Strandings Scheme and the Irish Whale and Dolphin Group Cetacean Stranding Scheme, whose records and tissue samples from beaked whale strandings in the North Atlantic helped to determine that the New Zealand specimen was genetically distinct from the True's whales found in the northern hemisphere.
The new discovery brings thte total number of beaked whale species to 24. They are described in the paper as some of 'the most visible inhabitants of the deep ocean', and the group includes some of the deepest diving mammals. True's whales are marked as being of 'Least Concern' on the IUCN Red List as they have been commonly sighted in the open ocean, however, little is known about the various species, and seven remain classified as 'Data Deficient'.
The study reports that Ramari’s beaked whales probably spend most of their time far from shore, hence the reason so few specimens have been discovered. As s a lot of time offshore in deep waters given so few specimens have been discovered. As the authors note in the study's introduction: 'The Earth's deep ocean remains less understood than the surface of Mars.'
The complete study, 'Speciation in the deep: genomics and morphology reveal a new species of beaked whale (Mesoplodon eueu)' by EL Carroll et al. 2021, can be found in Proceedings of the Royal Society B, 288: 20211213, doi.org/10.1098/rspb.2021.1213