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28 September 2017

What Happens To Wild Dolphins In A Hurricane?

Tragically, hurricanes Irma and Maria have caused widespread devastation to human communities on Caribbean islands and the US coasts, including loss of lives.

In the aftermath of these monstrous storms, we’ve been thinking about how wild dolphin populations cope?  What is the impact on their communities?   Of course, no one studies dolphins during a hurricane – that would be too dangerous. But researchers have looked at the consequences for dolphin communities, and these investigations clearly show that dolphins can suffer heavily in large storms.

Hurricane Katrina had a devastating impact on captive dolphins and wiped out about a third of one local wild bottlenose dolphin population in the Gulf of Mexico in 2005. In the early 2000s, the bottlenose and Atlantic spotted dolphins in the Bahamas lost many members of their communities in a hurricane.

Dolphins, like people, can have their lives and communities ripped apart. But, although we have no idea of the long-term emotional impact on individuals, dolphins are responsive and intelligent and, as a community, they adapt.

Bottlenose dolphinsIn one study, researchers found how dolphins restructured their social lives significantly after a hurricane. Lost members were ‘replaced’ by dolphins entering the community from outside; evidence of the complex and at the same time flexible nature of dolphin societies. One year later researchers observed a baby boom. Many mothers had lost their young but the community appeared to adjust with a sudden increased reproduction rate.

Even more intriguing was the study that found levels of aggressive behaviour between bottlenose and Atlantic spotted dolphins had decreased in the aftermath of a hurricane. The males of these two species were known to fight on a regular basis, but this behaviour reduced after the two communities both lost members.

We’re in the early days of research into the impact of hurricanes on whales and dolphins and we’ve much to learn. We know there can be a devastating impact on populations, followed by changes in behaviours to adjust. But we don’t yet know what happens in the longer term. A wild population might adjust to the impact of one major storm, but what if climate change means that such events become more frequent? If there is an increase in intensity and frequency, it will mean more dolphins dying.


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