One of the most mysterious and sad things about marine mammals are mass strandings. A dolphin or a whale can get disoriented and end being washed ashore, but what’s going on when this happens to a lot of them at the same time? A new study give us some light about the long-finned pilot whales strandings, the primary species in these cases.
Pilot whales are large dolphins, which can reach 20 feet, so it’s really difficult to move them to the sea again. For example, last year in New Zealand, where the mass strandings are usual, volunteers rescued 17 of 100 animals, and all of them returned to the beach and re-strand themselves. It is thought that the stranded whales are always members of the same families, from the same matriline or at least kins. I mean, there are two major ideas that we apply to strandings: they are from the same group, as they stranded at the same time all together, and usually a mother is close to her calf, so when they strand in lines you’ll find the mother and the calf next to each other.
According to researchers from the Auckland University, this is not as true as we thought. Analyzing mtDNA haplotypes (only inherited from your mother) of 486 individuals from 12 different strandings, in 9 of them they found multiple maternal lineages, and in all of them there were no correlation between spatial distribution and kinship. That’s not all, they found a spatial disruption on the proximity between the mother and their dependent calves. This offers another explanation: interactions between unrelated social groups for feeding or mating could break kinship bonds, and probably this is a major cause in stranding events. So, maybe, when a group is separated, they can get disoriented looking for their relatives! The study is quite relevant, as it’s not focused on environmental factors but on the animals and their behavior.
This discovery needs to be checked with more DNA analysis, and more stranding records. But if it’s true, and it looks like it is, is very important for the future of conservation projects! This helps us to understand the complicated social relationships between marine mammals and how to react to a stranding!
Which factor do you think plays a more prevalent role in marine mammal mass strandings: environmental causes or animal behaviour?Speak Up and let yourself be heard on behalf of marine mammals everywhere!