|Pilot whale stranding on Farewell Spit, South Island, New Zealand. Credit: Chagai via Wikimedia Commons.|
The researchers conducted genetic analyses of 490 individual pilot whales from 12 different stranding events and found multiple maternal lineages among the victims in each stranding. The bodies of mothers and young calves were often separated by large distances, and in many cases the mothers of calves were missing entirely from groups of whales that died in the strandings. This suggests that strong kinship bonds were disrupted prior to the actual stranding——and that these disruptions maybe played a role in triggering the strandings. Which challenges another popular hypothesis: that taking care of close maternal relatives may be the cause of otherwise healthy whales stranding.
The study has implications for people trying to save beached whales. "Rescue efforts aimed at refloating stranded whales often focus on placing stranded calves with the nearest mature females, on the assumption that [she] is the mother," says co-author Scott Baker, associate director of the Marine Mammal Institute at Oregon State University. "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.