Do Whales Commit Suicide?
Witnessing any dolphin or whale stranding live is a deeply moving experience; particularly when you end up accompanying an individual to the end of its life. My stomach still churns remembering the time that I encountered one in Scotland.
But the reasons behind such events remain mysterious. Dolphins and whales can strand together – most recently, ten long-finned pilot whales became stranded on a beach near Calais, seven of which died – but we can’t pinpoint a single reason why this happens. Instead, many different factors appear to be involved.
Some mass strandings are easy to solve, because the individuals involved are similarly sick or injured. In these cases, they strand because they are pushed inshore by currents as they ail and die. Alternatively, they head for shore because they are simply too sick to swim.
Harmful algal blooms, for example, have been linked to mass strandings of whales as far back as the Miocene. Epizootics – disease events among an animal population – are also a common culprit. A morbillivirus (related to our measles virus) outbreak among dolphins in the North Atlantic caused several mass strandings along the US eastern seaboard in 1987 and 1988.
Even whales make mistakes
Accidents happen, too. Naval exercises, which may involve the use of high-powered sonar, have been linked to mass strandings as individuals become confused, or get injured or injure themselves trying to flee. Like human divers who surface too quickly, some even get the bends (decompression sickness).
There are also long-term trends, which are linked to tougher environmental conditions. Perhaps food stocks are low, temperatures are unusually high or low, or pollutants enter the water. Any of these factors could cause the mammals to behave differently.