Pilot Whales Adopt Synchronized Swimming During Danger

Ever wondered how the cetaceans protect themselves from external threat?  An international team of scientists analyzed the mechanism they follow in order to defend themselves from both land and sea-based predators.

For this study the team observed the behavior of various groups of cetaceans in the Strait of Gibraltar and Cape Breton in Canada belonging to the Globicephala melas species.

They studied nearly 300 pilot whales residing in the Strait of Gibraltar and Cape Breton.

This study was headed by the University of Aberdeen in collaboration with the Doñana Biological Station and Conservation and the Information and Study on Cetaceans group. The researchers wanted to see how the whales interacted with each other and in turn study their social structure.

The researchers learnt an important fact during their observations that these whales use synchronized swimming when they identify the presence of an external threat.

"The important point is that we compared two different populations: one inhabiting the Strait of Gibraltar which is exposed to predators (boats in this case) and another with an ecotype where there are not so many boats (Cape Breton in Canada). The pilot whales are social species and we were interested in seeing how mothers teach their young, for example. We observed that they use synchronized swimming when in danger,"  explained Renaud de Stephanis, researcher at the Biological Station of Donana and co-author of the study.

The scientists gathered samples in an area of 23,004 km in the Strait of Gibraltar between 1999 and 2006. They captured at least 4,887 images of the dorsal fins of whales to compare them with those in Canada.

"They swim in complete synchrony both in the Strait of Gibraltar and Canada. When sea traffic or whale watching vessels are nearby, the whole group collectively reacts to such external stimuli. When we arrived at the watching area they were swimming at their normal rhythm but after 10 or 15 minutes near to them, the mothers and their young began to swim in a synchronized manner in alert position. This is a sign of affiliation to the group," added the expert.

The researchers stated that cetaceans also have a social structure formed by permanent partnerships. Unlike the bottlenose dolphins, these cetaceans spend their lifetime within the same group and do not interchange between different groups.

"As such, when we began observing the whales up close, they tended to spend quite some time on the surface. However, the longer we spent nearby, the longer they stayed under water. This behavioral change could affect their energy levels, since they then have to make more of an effort to protect themselves and their young. In turn this limits hunting time, which means that they cannot feed their young properly," concluded the researcher.

he study was published in the journal, Behavioral Processes.