Orca pod spotted off north-west coast in Sutherland renews interest in UK's only resident killer whales
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Five killer whales were spotted on Friday from a remote nature reserve island.
The pod - including a calf - was seen 200 yards off Handa in Sutherland, in a sighting logged with the Hebridean Whale and Dolphin Trust.
The Trust confirmed that the orca were not from the UK's only resident killer whales, which may be down to just two members, researchers now increasingly believe.
And pollution may have played a significant role in their demise and why the group have not produced a single calf in more than a quarter of a century.
The Hebridean Whale and Dolphin Trust has issued photographs of the missing six and appealed for any sightings of any orca in its waters.
Research is also being carried out to try and finally determine what has happened to the disappeared who have not been spotted for over six years, despite being known to form close family and social bonds.
The group of eight is distinguishable by their unusual sloping eye patch and larger size.
The pod is made up of four males and four females and normally reside in the Hebrides.
They have been studied over five decades. Two are still regularly seen, but now a new appeal is being made is to try and discover what has happened to the other six.
The known remaining pair - known as John Coe and Aquarius – have been spotted regularly recently along the west coast.
HWDT now believe they may be the only surviving members of the famous west coast community.
A shark is suspected of biting a chunk out of the tail fluke of John Coe - the male orca can be easily identified by a notch on its dorsal fin.
A ninth member of the west coast community pod, Lulu, was found dead on the Isle of Tiree in 2016 after becoming entangled in fishing lines.
Tests later revealed her body contained among the highest levels of polychlorinated biphenyls, or PCBs, ever recorded.
The chemicals were banned from the 1970s, but are still in the environment.
There are worries that the entire west coast community is barren thanks to the high concentration of PCBs. Lulu’s body contained 950mg/kg, of PCBs – more than 100 times the 9mg/kg limit above which damage to the health of marine mammals is known to occur.
The findings add to strong evidence that the pod is doomed to extinction – there are no records of any new calves being born in the last 25 years.
The pod’s tenth original member, called Moon, was found dead on an Isle of Lewis beach in 2008. A postmortem revealed that it had eaten part of a minke whale - still the only UK record of orca predating on minke whales.
“There is no record of the 'disappeared six' stretching back many years. It is not looking good," admitted Morven Summers, spokesperson for the HWDT.
"They are long lived and we do have photographic records of them but they have not been seen for so long now.
"They could have moved away or sadly died. We are conducting new research into this topic, but we would like people to send us photos of any killer whale along the west coast to try and find them. We can identify them with certainty from our database.
"We would like to determine exactly what has happened to this pod and people can help us with their sightings and put an end to this mystery."
Scotland's seas are also believed to be home to semi-resident groups of orcas. At least one pod arrives from Iceland each spring to raise young and to hunt.
Adult killer whales measure 5.5 to 9.8 metres in length and can live for up to 90 years; females are generally smaller and longer-lived than males.
The adult males’ dorsal fin is the largest of all cetaceans at up to 1.8 metres and is an important identification feature.
The killer whale is one of the ocean's top predators. Different pods of killer whales have different feeding preferences and their prey includes fish, shark, octopus and squid, as well as birds, seals and other cetaceans.
They often hunt co-operatively and in silence, especially when pursuing marine mammal prey. The West Coast Community are known to feed on other marine mammals such as harbour porpoises and killer whales around Shetland and Orkney have been recorded feeding on seals.
Handa Island lies a few miles off the west coast of Sutherland. It is owned by Scourie Estate and managed as wildlife reserve in partnership with the Scottish Wildlife Trust.
There have been no full-time inhabitants since 1848 but during the summer Handa attracts around 200,000 birds including guillemots, kittiwakes and fulmars.
Seasonal rangers live on the normally uninhabited island, which attracts thousands of visitors.
In the 19th century, Handa was recorded as having a population of around 65 people. The islanders had a parliament, similar to that of St Kilda, which met daily, and a female-centric society where the oldest widow on the island was considered its 'Queen.'
But despite a healthy diet of oats, fish and seabirds, the remaining islanders decided to abandon their homes for the mainland 171 years ago as a result of the potato famine.