"If kinship-based behavior was playing a causal role in strandings, we would expect that whales in a stranding event would be related to one another through descent from a common maternal ancestor, such as a grandmother or great-grandmother and that close kin would be clustered on the beach," Oremus said. "Neither of these was the case."
Because of the separation of mothers and calves, or in some cases, the outright absence of mothers among the victims, the study has important implications for agencies and volunteers who work to save the stranded whales, Baker said.
"Rescue efforts aimed at 'refloating' stranded whales often focus on placing stranded calves with the nearest mature females, on the assumption that the closest adult female is the mother," Baker pointed out. "Our results suggest that rescuers should be cautious when making difficult welfare decisions such as the choice to rescue or euthanize a calf based on this assumption alone."
Long-finned pilot whales are the most common species to strand en masse worldwide, the researchers noted, and most of their beaching events are thought to be unrelated to human activity unlike strandings of some other species. Both naval sonar and the noise of seismic exploration have been linked to the stranding of other species.
The phenomenon is not new. In fact, mass strandings of whales or dolphins were described by Aristotle more than 2,000 years ago and were thought to have some kind of natural cause, Baker said, although it is unclear what that may be.
"It is usually assumed that environmental factors, such as weather or the pursuit of prey, brings pilot whales into shallow water where they become disoriented," Baker said. "Our results suggest that some form of social disruption also contr
|Contact: Scott Baker|
Oregon State University