The coast of the UK is not well-known for its whale watching opportunities. However, the seas around the British Isles do receive regular visits from an array of marine mammals, from the diminutive harbour porpoise to the 70 ton fin whale. And Scotland’s west coast is home to the UK’s only resident orca population, a group of eight individuals that scientists now believe is doomed to extinction.

The pod, which today consists of four males and four females, has not produced a single new calf in the 25 years they have been scientifically monitored, nor have any new animals entered the family. Last year, the “west coast community” lost a key female, Lulu, who was washed onto the Isle of Tiree after getting entangled in a fishing rope.

“The chance of survival for this group is sadly very slim”, says Dr Lauren Hartny-Mills from the Hebridean Whale and Dolphin Trust (HWDT), “but it is unclear why they have not been able to produce any calves. It could be the result of human activity such as pollution which can affect reproductive success, but it may also be the result of more natural processes and the female killer whales could now be too old to reproduce.”

Tourists on ferry trips can help provide vital information about the whales (Getty)

Scientists are yet to draw a definitive link between the plight of the west coast orcas and the prevalence of industrial toxins in European waters, however it is highly likely that a chlorine compound known as polychlorinated biphenyls (PCBs) has played a part in their difficulties.

Once applied to industrial fluids in factories around the world, PCBs have been bringing about health defects in animals for decades. The seas around Europe are known to be a particular hotspot for these substances, which are now mostly banned from use but take a very long time to decay. Killer whales are the largest members of the dolphin family, and are right at the top of the oceanic food chain, making them particularly susceptible to high concentrations of contaminants.

They also have the second-largest brains of all ocean mammals, and are believed to be one of the smartest animals on the planet. Like elephants, this intelligence helps these whales to build complex family lives as well as sophisticated hunting techniques. They have very tight social groups, and display a rare behaviour in the animal kingdom where males remain with their mothers for the entirety of their lives, only leaving their maternal group in search of mating opportunities.

Their apparent intelligence makes them one of the world’s most successful predators. Orcas are found in every ocean, and in some parts of the world have been known to feed on other whales, including the world’s largest animal, the blue whale. It is thought that the west coast pod mostly feeds on other marine mammals, principally seals.

What little we do know about this group of animals has been derived from both scientific study and sightings from amateur observers. “Much of what we know about the west coast community is thanks to the involvement of the public,” explains Pippa Garrard, HWDT’s Community Engagement Officer. “With the pod covering such a large area, we depend on people to report their sightings and send in photographs, from fishermen to tourists.”

While other killer whale pods are migratory, and regularly enter the waters of Scotland in pursuit of prey, the west coast community is the only group known to stay exclusively off the UK coast. According to Dr Andy Foote, a marine biologist who studied this group, the west coast killer whales have also been sighted off Pembrokeshire in Wales, and Cork, Ireland, as well as Scotland.

Jon Coe the whale is recognisable by the chunk missing from his dorsal fin (HWDT/Nienke van Geel) (Nienke van Geel)

Surprisingly, recent research by Foote and others has also shown that the pod is more closely related to the “Type 2” orcas found in the Antarctic, than the smaller “Type 1” whales that visit the UK’s shores. This might be one reason why the pod doesn’t interact with the other whales that enter the area, further contributing to their isolation and breeding issues.

The HWDT has given the whales nicknames: Nicola, Moneypenny, Floppy Fin, John Coe, Comet, Aquarius, Puffin and Occasus. They’re identifiable through marks and coloration on the parts of the body that are visible when they surface.

As his name suggests, Floppy Fin has one characteristic in common with Keiko, the captive whale who starred in the 1993 film Free Willy. Male killer whales sport tall dorsal fins that can grow up to 2m high, but this one is permanently “flopped” to one side, a common condition in captive animals, but a relative rarity for wild orcas. Tilikum, the large male orca from the 2013 documentary Blackfish, also had “dorsal collapse”.

Dead whales beached on the North Sea coast Show all 8 1 /8 Dead whales beached on the North Sea coast Dead whales beached on the North Sea coast Two dead sperm whales are seen washed up on a beach near Skegness in northeast England. Four sperm whales believed to be from the same pod washed up on beaches in northeast England. Three whales were found on a beach near Skegness and one died on Hunstanton beach AFP Getty Dead whales beached on the North Sea coast 50ft sperm whale beached in Norfolk The dead 50ft (14.5m) young adult male sperm whale beached in Norfolk, which was was part of a group of six spotted in the Wash at Hunstanton, is believed to have been part of a pod that stranded and died in the Netherlands PA Dead whales beached on the North Sea coast 50ft sperm whale beached in Norfolk The dead 50ft (14.5m) young adult male sperm whale beached in Norfolk, which was was part of a group of six spotted in the Wash at Hunstanton, is believed to have been part of a pod that stranded and died in the Netherlands PA Dead whales beached on the North Sea coast 50ft sperm whale beached in Norfolk The dead 50ft (14.5m) young adult male sperm whale beached in Norfolk, which was was part of a group of six spotted in the Wash at Hunstanton, is believed to have been part of a pod that stranded and died in the Netherlands PA Dead whales beached on the North Sea coast 50ft sperm whale beached in Norfolk The dead 50ft (14.5m) young adult male sperm whale beached in Norfolk, which was was part of a group of six spotted in the Wash at Hunstanton, is believed to have been part of a pod that stranded and died in the Netherlands PA Dead whales beached on the North Sea coast 50ft sperm whale beached in Norfolk Two of three dead sperm whales that have washed up on a beach in Lincolnshire, just a day after another was beached in Norfolk PA Dead whales beached on the North Sea coast One of three dead sperm whales that have washed up on a beach in Lincolnshire, just a day after another was beached in Norfolk PA Dead whales beached on the North Sea coast Photo taken from the Twitter feed of the @RNLIskegness of one of three dead sperm whales that have washed up on a beach in Lincolnshire, just a day after another was beached in Norfolk PA

Another male, John Coe, has a distinctive nick in his fully upright dorsal fin, as well as a large patch missing from his tail fluke, presumed to be the result of a shark attack.

While the west coast community is likely to die out, the UK’s seas remain a fertile fishing ground for both other pods of killers and other species of whale. Although they may not be as isolated as the Scottish orcas, the risks to these animals through PCBs, discarded fishing nets and disruption to their echolocation are still significant.

“There are two regions in the world where there are high concentrations of PCBs”, says Dr Paul Jepson from the Zoological Society of London (ZSL). “North America, where there might be around 600,000 tonnes of PCBs during the period in which they were made. Then Europe where we made slightly fewer.”

The chemicals can remain inside an animal’s body for years, causing problems for their reproductive and immune systems. A recent ZSL report into the effects of the toxins concluded that the prevalence of PCBs found in whale blubber samples “greatly exceed concentrations at which severe toxic effects are known to occur”.

Killer whales have very tight knit social groups (HWDT/Nienke van Geel) (Nienke van Geel)

A notoriously robust chemical, PCBs are believed to be re-entering the oceans through un-lined rubbish dumps and dredging, which stirs up the sea floor and brings the toxins back into the water.

Dealing with these toxins is extremely expensive, and not high up the environmental agenda for most European countries, despite being signed up to the Stockholm Agreement which commits the signatories to taking action on PCBs.

In the US, the Environmental Protection Agency (EPA) identifies the areas that are most contaminated by the pollutants, such as brownfield industrial sites, but also rivers and estuaries, where the toxins come up through the sediment and into the water. The EPA then decontaminates these areas by physically removing huge amounts of sediment.

Unsurprisingly, the costs of such operations can run into billions of dollars, and that’s before you try to destroy the chemicals themselves.

“For PCBs, you have to heat them to about 1200 degrees for about five minutes in enriched oxygen, just to destroy them properly”, says Dr Jepson. “Very few incinerators are able to do that. If you don’t heat them to the right temperature, for the right period, you risk creating dioxins, which are one of the few chemicals that are even more toxic than PCBs”.

Out of sight for the majority of Britons, the UK’s whales and dolphins are poorly understood but attract huge amounts of public attention during mass strandings. While a solution to the pollution problems they are facing is yet to be found, the HWDT is encouraging the public to help them build a better knowledge of these animals.