Strandings of a neonate and a pregnant Sowerby's beaked whale (Mesoplodon bidens(Sowerby, 1804)) in Ireland

Abstract

Sowerby's beaked whale is a deep-diving cetacean species specialized to live in the deep waters of the North Atlantic, including offshore Irish waters. Sightings of Sowerby's beaked whales in this area are infrequent and a substantial increase in our knowledge of their presence comes from recent static acoustic monitoring (SAM) and passive acoustic monitoring (PAM). However, most information on this species has been derived from stranding records, which provide opportunistic insights into this elusive species' cryptic life history. Here we report on the live stranding of a 1200 mm long neonate and an adult 5 m female Sowerby's beaked whale in July 2015 and on the stranding of a 4.9 m pregnant female in September 2020 with a 495 mm long male foetus in the south-west of Ireland. These stranding events provide an important insight into the reproductive life history of this species and provide further evidence that Sowerby's beaked whales calve in offshore Irish waters.