Abstract

Mass strandings of beaked whales (three or more whales) were rare prior to 1960.¹ However, in the early 1960s, the frequency of such strandings markedly increased, as did the number of species involved. We examine worldwide mass strandings of beaked whales from 1838 to 2010 and propose reasons for the changes after 1960. We documented 113 beaked whale mass stranding events (MSEs) and classified them in two types: typical and atypical. In a typical stranding, all the whales strand at the same location, whereas in an atypical stranding all the whales do not strand at the same location.² Thirty-five of the 113 MSEs involved typical strandings of Gray's beaked whales, Mesoplodon grayi; we were unable to determine their probable cause. Only nine MSEs occurred from 1838 to 1960 but 104 occurred between 1961 and 2010. Prior to 1961, only three of the 21 currently recognized species of beaked whales were involved in MSEs. After 1961, another nine species of beaked whale were also involved in MSEs. All MSEs before 1960 were typical but after 1961 many of them were atypical. Forty-two of the 113 MSEs involved Cuvier's beaked whales, Ziphius cavirostris, and at least half of them were atypical and were either strongly correlated with naval activities off the Bahamas, Canary Islands, or Greece or occurred in areas where U.S. naval fleets were based: Japan, Puerto Rico, and Italy. No known atypical MSEs of Cuvier's beaked whales have occurred in other parts of the world. The first atypical MSEs coincided with the start of wide-scale use of tactical mid-frequency sonar by the U.S. Navy in the early 1960s. Some of these atypical strandings involved more than one species. The U.S. Navy is exploring possible mitigation measures. However, studies are still needed to better understand beaked whale population sizes at the local level. Studies are critical in areas where local resident populations are subject to repeated naval operations, as shown by repeated MSEs, as well as impacts from bycatch. The impacts of human-related deaths are compounded by the very low reproductive rate in beaked whales and possible sonar-related disruption of social behavior that might reduce whale survival.

Acknowledgements

Numerous people helped to collect, organize the basic stranding records, and discuss these stranding events including Dee Allen, Alan Baker, Kenneth C. Balcomb, III, John Bannister, Peter Best, Nick Gales, Rosemary Gales, John Hildebrand, Mary Jacobs-Spauling, Toshio Kasuya, Cath Kemper, Carl Kinze, Kaoru Kohyama, Tadashi Kubota, Keiko Meshida, K. Mori, M. Nakajima, Hiroshi Ohizumi, D. Viale, L. Weilgart and H. Whitehead. Phil J. Clapham William F. Perrin, Douglas P. DeMaster and especially Katherine Ralls provided valuable comments of various drafts of our manuscript. Travel support to collect data on the Japanese MSEs of Ziphius was provided by the U.S. Marine Mammal Commission.

* Presenting author

Literature Cited

1.  Frantzis, A. 1998. Does acoustic testing strand whales? Nature. 392:29.

2.  van Heel, WHD. 1962. Sounds and Cetacea. Netherlands Journal of Sea Research. 1:407–507.