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.

In the first seven months of 2008, eighteen Cuvier's beaked whales (Ziphius cavirostris), four Sowerby's beaked whales (Mesoplodon bidens), five unidentified beaked whales and twenty-nine long-finned pilot whales (Globicephala melas) were reported stranded in the UK and Ireland. Decomposition of those animals investigated puts the predicted time of death at mid-January. Concerns that an unusual mortality event had taken place prompted further investigations. Most carcasses were too decomposed for necropsy. A summary of findings is presented here. Although the initial stranding of five Cuvier's beaked whales in Scotland shared some similarities with atypical mass stranding events linked in time and space to mid-frequency naval sonars, there were two important differences with the remaining strandings during this period. First, the geographical range of the event was very wide and second, the strandings occurred over a prolonged period of several months. Both of these factors could be related to the fact that the mortalities occurred offshore and the carcasses drifted ashore. The cause(s) of this high number of strandings of mixed offshore cetacean species during this period remain undetermined.