A review of beaked whale (Ziphiidae) stranding incidents from the inshore waters of eastern Canada

Abstract

Cetaceans of the family Ziphiidae (beaked whales) include some of the least known whale species. We review 78 ziphiid stranding incidents from the inshore waters of eastern Canada (defined as the Atlantic provinces north to central Labrador, including the Gulf coast of Quebec, from ~latitude 43.5°N to 55.0°W), with outcomes that involve 84 individual whales. This includes all eastern Canadian ziphiid stranding incidents known to us from the first report of 24 February 1934 to 31 December 2021 for the five species documented from eastern Canada: Northern Bottlenose Whale (Hyperoodon ampullatus), Sowerby’s Beaked Whale (Mesoplodon bidens), Blainville’s Beaked Whale (Mesoplodon densirostris), True’s Beaked Whale (Mesoplodon mirus), and Cuvier’s Beaked Whale (Ziphius cavirostris). Northern Bottlenose Whale (41.0% of incidents, 40.4% of individuals) and Sowerby’s Beaked Whale (46.1% of incidents, 46.4% of individuals) have stranded most frequently, with the remaining three species stranding very rarely in the region. An average of 0.55 individual ziphiids/year were reported stranded from 1934 to 1999 in eastern Canada, but since 2000 this has increased to an average of 2.2 stranded individuals/year. Much of this increase is undoubtedly due to improved reporting, but other factors may also be involved. We emphasize the importance of the ongoing documentation of cetacean stranding incidents, but especially the need to better understand causes of ziphiid mortality, particularly for those species that reach the edge of their range in the western North Atlantic or are of conservation concern.