Up Close and Personal With… Seals

Seals are a popular marine creature the world over with their playful and inquisitive nature, enormous dark eyes and lazy habit of sunbathing on quiet corners of our beaches. Whilst they are often clumsy and comical on land as they shuffle across the sand, in the water they put on quite a different show filled with acrobatics, speed and grace. Their extraordinary swimming abilities come from their fin shaped feet which actually gave these creatures their name. Seals are scientifically known as pinnipeds which translates from Latin to ‘fin-footed’. There are 33 species of pinniped in Earth’s oceans and these can be split into three different groups: walruses, eared seals such as sea lions and fur seals and finally earless seals. Earless seals are considered the true seal species and include grey seals, elephant seals and leopard seals. In contrast to eared seals, their ears are hidden internally under their blubber but they are also unable to move their hind flippers under their body which makes them slower and less agile on land than flexible sea lions.

Pinnipeds have a massive distribution and can be found on every continent on Earth although most prefer to hang out in cold water environments closer to the poles. Seals also vary enormously in size, with the mighty southern elephant seal weighing even more than both rhinos and hippos! On the other end of the scale, Baikal seals can weigh as little as 100 pounds. These tiny seals are also unique in that they spend their entire life within the fresh waters of Lake Baikal in Siberia whilst all other seals live within the ocean, although they may venture upstream into estuaries and rivers whilst on the hunt for food. Most of the pinniped species feast on fresh fish, however there are a couple of exceptions. Leopard seals live in the icy waters of Antarctica and supplement their fish diet with penguins and even other seal species as they must consume enough food to maintain their core body temperature in the harsh environment. On the other side of the world, walruses inhabit the cold waters surrounding Canada, Greenland and Russia and their Latin name Odobenus rosmarus actually translates to ‘tooth walking seahorse’. Their long teeth are used as axes to help them grab onto the ice and pull themselves out of the cold ocean as well as to create breathing holes in the ice. Their whiskers are just as sensitive as our fingertips and are used to detect shellfish on the dark seabed. Once a tasty clam is found, they use their powerful mouths to suction up the creature before searching for the next morsel. Part of what gives seals their enigmatic nature is their huge dark eyes and these are actually very useful for gathering the maximum amount of light deep under the sea surface which helps them to hunt. However, their whiskers are so sensitive that even blind seals can survive in the wild by using their whiskers to locate food and guide them through the underwater environment.

Unfortunately, seals’ friendly nature and charm have not allowed them to escape any of the threats which now lurk in our oceans. Historically, seals were hunted throughout the world for their fur which was turned into fashionable items and sometimes also their oil which was used as a machine lubricant. This practice left many seal species teetering on the edge of extinction whilst others, such as the Caribbean Monk Seal, sadly tipped past this point and have been lost from our planet. Today, the demand for seal products is dying out and new rules and regulations are limiting the number of seals hunted by humans, although that is not to say that this practice has completely disappeared.

Only last year was the shooting of seals in Scotland banned. Seals were allowed to be killed by salmon farmers if they were thought to be a threat to their profitable fish stocks, a method which has been contested by many conservationists. In 2020 however, this practice was halted as their trade agreements with America came under threat as the shooting of seals breached the US regulations which protect the welfare of wild marine mammals. In order to keep their large buyer of salmon, Scotland has now switched to using acoustic devices to scare hungry seals away instead.

In fact, the threat of angry fishermen is a longstanding source of danger for seals as some believe that they steal their harvest and cause an overall decline in fish stocks. This had led to some fishermen deciding to kill seals in order to take out the competition. Yet research shows that seals can actually benefit fish stocks, with the harbour seal, for example, feasting on the predators of commercially important fish. Pinnipeds, as with many other species, are essential for maintaining the natural balance of the ocean ecosystem by controlling prey and predator numbers whilst also forming a food source themselves for larger hunters. In some areas, seals are just as desperate for fish as humans are as their traditional food stocks are declining, leaving local seal pinniped populations lacking essential nutrients.

The indirect threat of fishing however, is a much larger cause of population decline in pinnipeds. Ghost fishing is where old fishing lines, nets and buckets are lost to the sea and travel around the globe via ocean currents. With their inquisitive and playful nature, seals often approach these objects to find out more and start a new game, yet this often leads to them becoming entangled in fishing rubbish with no way of getting out. Over time, this can inhibit both their swimming and their growth, limiting their feeding and making them more susceptible to predators. Plastic trash from the land also threatens these creatures which often accidentally consume microplastics suspended in the water. Plastic is a great host for toxins and chemicals which then travel through marine creatures’ bodies and can lead to a plethora of diseases and aliments. Yet unfortunately, human impact on these wild animals doesn’t stop there either. With increasing numbers of tourists and visitors flocking to our coastlines, our beaches and rocky shores are becoming ever more crowded and noisy. Seals prefer quiet and peaceful coves and loud human noises can easily scare these creatures away from their resting spots or breeding areas both temporarily and permanently depending on the level of disturbance.

Finally, climate change is rapidly becoming a threat to those seals which live in the polar regions. Many cold-water seals rely on sea ice for resting, breeding and raising young, with ringed seals building caves in the snow to shelter their offspring. As the sea ice melts increasingly early each summer, pups have fewer weeks to feed on their mother’s milk and gain essential fat stores whilst they are also at an increased risk of predation from polar bears which prowl along the snow. With the effects of climate change occurring so quickly, some seals are struggling to find a balance in their evolving ecosystem. Livingston Island lies in the Antarctic and due to a large interest in hunting here in the past, scientists have lots of data about the numbers and whereabouts of seals. Up until the 1990s, it was rare to see more than two leopard seals on Livingston Island but recently researchers have spotted roughly six swimming in the nearshore waters whilst one lucky researcher spotted 30 hauled out on the snow. This might not sound like a great number of seals, but leopard seals are apex predators which normally hunt alone within their territory. Imagine having that many grizzly bears or ferocious tigers on your local beach! Normally, leopard seals hunt for penguins and crabeater seal pups which can be found on offshore ice floes. Yet as the ice is melting, leopard seals are struggling to find their prey on floating ice and so have instead turned to solid pieces of land to hunt, with Livingston’s fur seal pups forming their new diet. This however has caused the local fur seal population to drop by a massive 80% in only 15 years as they struggle to adapt to the sudden threat of predation. When crabeater seals were the prey, their relationship was fairly sustainable as crabeater seals form the largest seal population on Earth, yet Livingston’s fur seals are a relatively small colony which are now facing extinction.

As you can see, there are many different events which are threatening the peaceful existence of our pinnipeds and in fact many of these creatures are now on the red list for endangered species. Yet with seals being found on every continent, hauling out on the same familiar beaches at predictable times, they also form one of the most accessible and easy to spot marine species in the world, whether they are the large grey seal colonies on Britain’s beaches or the sea lions snoozing on California’s Pier 39. It is for this reason that so many people feel connected to these enigmatic species and conservationists are hoping that they could become an icon for marine conservation where they are used to engage the public in issues such as plastic waste, unsustainable fishing and habitat loss. By using species which split their time between the waves and the sand, conservationists hope to highlight how our actions on the shore, both positive and negative, can create a much wider effect out at sea. In return, it is hoped that a new sense of purpose and affection towards marine environments will trigger a surge in conservation action which can help support seal populations both survive and thrive in their changing home.

By Neve McCracken-Heywood