NEWPORT, Ore. Pilot whales that have died in mass strandings in New Zealand and Australia included many unrelated individuals at each event, a new study concludes, challenging a popular assumption that whales follow each other onto the beach and to almost certain death because of familial ties.
Using genetic samples from individuals in large strandings, scientists have determined that both related and unrelated individuals were scattered along the beaches and that the bodies of mothers and young calves were often separated by large distances.
Results of the study are being published this week in the Journal of Heredity.
Scott Baker, associate director of the Marine Mammal Institute at Oregon State University, said genetic identification showed that, in many cases, the mothers of calves were missing entirely from groups of whales that died in the stranding. This separation of mothers and calves suggests that strong kinship bonds are being disrupted prior to the actual stranding potentially playing a role in causing the event.
"Observations of unusual social behavior by groups of whales prior to stranding support this explanation," said Baker, who frequently advises the International Whaling Commission and is co-author of the Journal of Heredity article. The OSU cetacean expert is a professor in the Department of Fisheries and Wildlife at the university's Hatfield Marine Science Center in Newport, Ore.
The mass stranding of pilot whales is common in New Zealand and Australia, involving several thousand deaths over the last few decades, according to Marc Oremus of the University of Auckland, who is lead author on the study. The researchers say their genetic analysis of 490 individual pilot whales from 12 different stranding events showed multiple maternal lineages among the victims in each stranding, and thus no correlation between kinship and the grouping of whales on the beach.
|Contact: Scott Baker|
Oregon State University