What Exactly are Marine Mammal Strandings?

Sadly, it seems that whale strandings have been all too common in the news since the end of summer. Devastating tales from Sri Lanka and Tasmania have filled headlines as hundreds of marine mammals accidentally crossed the border between their underwater world and our terrestrial one. Despite whales evolving from four-legged land mammals 50 million years ago, the sand is no longer a place where they belong and is, instead, wrought with danger. Yet what exactly drives these intelligent creatures onto our shores and into trouble?

Strandings, or mass beaching events as they are also known, occur around the globe on a surprisingly regular basis and impact a variety of marine mammals including whales, dolphins and porpoises. Whales which normally spend most of their lives diving into the deeper parts of the ocean seem to be the most frequent casualties, from sei whales beaching in the fjords of Chile to sperm whales grounding ashore along the Northern coasts of Germany, France and Holland. Despite strandings being a fairly common phenomenon, scientists still lack a clear idea of why they occur but we do know that they often seem to take place in very shallow areas of ocean where the seabed forms a gentle sandy slope. Despite the urge to point the finger once again at humans each time a mass beaching event occurs, there are actually a few reasons why they are a natural phenomenon. In fact, 40 whale skeletons were uncovered less than a decade ago on Chile’s northern coastline and scientists have dated the bones to be between six and nine million years old! This may be the very first recording we have of a mass stranding event and it was thought to be driven by the pod of whales consuming fish contaminated with harmful natural toxins which form what are known today as ‘red tides’. These toxins are the result of natural algal blooms and would have led to the whales becoming sick and weak, leaving them seeking the safety of shallow waters.

Disease or illness is still thought to be one of the most common drivers of beaching events amongst marine mammals. Once a member of the pod becomes unwell, they are likely to travel towards shallow coastal waters where they can easily come to the surface to breathe without having to summon the energy for the long swim back up from the dark ocean depths. Yet whales and dolphins are extremely social animals, living their entire lives within close knit pods, together migrating thousands of miles and hunting for large schools of fish. So when one injured individual turns for the shore, the rest of the pod feel compelled to follow and help their family member. Yet the search for the shore often leads whales into unfamiliar territory where they may get caught in strong tides or lose their sense of direction as they focus on aiding the sick member of the group. The alien sloping sand banks can easily confuse the echolocation whales use to navigate and a combination of all these factors can quickly lead to mammals getting into trouble as they are swept onto the hard sand of the coastline.

Heavy rolling storms with fearsome winds and currents are another natural hazard which could drive our whales and dolphins onto our beaches, whilst sometimes it is thought that pods get so distracted chasing a particularly tasty squid or swarm of krill that they simply do not realise how shallow the water beneath them has become. Yet an increasing amount of research is slowly bringing to light the human activities which are adding to the frequency of strandings. Often, military activity uses sonar systems to detect enemy submarines, however these loud slow-rolling sound waves travel under the water and disturb the echolocation used by our marine mammals for navigation, communication and hunting. Seismic surveys which are used to detect the presence of underwater oil also have a similar impact which can have devastating effects. In Europe this summer, 29 rare beaked whales were reported stranded on Northern beaches in a rare event occurring at a similar time to military activity in the area. Whilst the two are not concretely linked, we do know that sonar can scare deep dwelling whales, causing them to rise to the surface far too quickly and suffer from decompression sickness which can lead to muscle pain, cramp, nausea and even death. The impact of sonic waves travelling through seawater can be particularly frightening for whales living in the remote parts of our oceans as they live in relative peace and quiet, unaccustomed to sudden loud noises. Sonar can even cause whales to be less vocal and stop hunting for food and so pods of scared, quiet and hungry whales are driven dangerously close to the coast.

Once marine mammals have beached, we have only a limited amount of time to be able to save them. Just as we aren’t designed to live under the waves, whales have not evolved to live above water and quickly overheat in the open air whilst they are unable to catch food which also happens to be their sole source of freshwater. In the ocean, whales make their great size seem majestic, yet on land, the sheer weight of their bodies is too much to handle. In water, gravity pulls equally in all directions but above the surface, gravity pulls all of their body weight down to rest on their lungs, leaving them with organ damage within a matter of hours. So humans really only have a very small window of time to save these beautiful creatures and all our efforts are at the mercy of the tides, the weather, the remoteness of the location and the corrosive saltwater which likes to eat away at our mechanical aids. Our ability to help stranded animals also depends on their current health condition and their size. Dolphins and small whales can be re-floated by a team of determined volunteers using the aid of speakers playing out recorded whale songs to help lure them back out into the waves. Sometimes predator calls are used instead alongside the old-fashioned method of banging on metal pipes in a bid to scare away individuals who are not yet stranded but in perilously shallow water. Yet sperm whales can weigh up to 57,000 kilograms and so saving them relies on tractors, boats, cranes and slings. For these enormous animals, volunteers are left keeping them cool, hydrated and calm until heavy machinery help arrives.

In early November, 120 pilot whales beached themselves on the white sands of Sri Lanka. Sailors from the navy were joined by local volunteers to work through the night to save the wildlife the country prides itself upon. Luckily, there were some off road enthusiasts amongst the crowd of volunteers who parked their trucks along the beach and switched on the flood lights to allow the rescue mission to continue throughout the night. Others brought their jet skis and small boats to the scene, to help tow the whales off the sand and back into the water. This inspiring community persevered throughout the dark, even obtaining curfew passes from authorities to allow them to breach Coronavirus restrictions in order to save almost the entire pod of whales.

Over in Tasmania in September, Australia saw their worst mass beaching event ever as 470 pilot whales were driven onto the shore. Pilot whale pods can contain up to 1,000 individuals and so the straying of a few members of the group can lead to significant disasters for the local whale population. Again, volunteers pulled together to save these peaceful animals by first placing a sling under each whale before pulling and coaxing it off the sand. Once the individual was slightly buoyant, a local boat was used to tow the whale half an hour from the shore into deeper water where it was hoped they wouldn’t turn straight back around and re-join their beached pod. These community efforts around the world to save our precious wildlife in the face of disaster are so inspiring and can give us hope that our population really does care about the future of our delicate oceans.

So what can you do to help our poor lost whales and dolphins when they accidentally emerge onto our shorelines? Each country has an emergency strandings helpline which you can ring if you spot a marine mammal in need of rescue. By saving this number in your phone, you can quickly alert trained professionals to the issue and pass on details such as location, species, number of individuals and even photos to help rescue teams prepare the right equipment. If you want to go one step further, you can even train to be a volunteer marine mammal rescuer who will be on call to help try and save as many lives of our wild ocean creatures as possible. What reward could be better than that?

By Neve McCracken-Heywood