The blue whale is a surprising occasional visitor to Britain’s offshore waters. Though once hunted to the brink of extinction, these endangered giants can still sometimes be spotted in the deep seas around the north and west of Scotland, and even off Cornwall.
From their incredible size to their haunting song, here’s everything you need to know about the world’s biggest mammal and its rare appearances in the UK.
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The most common whale in UK waters is the minke whale, the smallest of the baleen whales. Larger whales are occasionally spotted further out to sea. The blue whale is the largest of them all – the biggest animal to have ever lived on Earth.
How big are blue whales?
Whales have to be big – as a mammal living in the ocean, which gets much colder than land, they have to be big enough not to lose too much body heat to the surrounding water. Blue whales are the biggest, and can grow to 33 metres, and weigh 180,000kg if female, or 150,000 if male.
In fact, it’s so heavy that it would be crushed by its own weight on land – as the buoyancy of the water supports its massive body. Without the support of water, its internal organs would be compressed, and its skeleton would collapse under the strain.
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What do blue whales eat?
A blue whale’s diet is almost exclusively made up of krill. During the summer months, they consume as many as 40 million krill a day. They take in large volumes of water in their throats, and then expel the water to trap the krill in the baleen (bone) fringes, which sit in place of teeth.
How loud is a blue whale's song?
The song of a blue whale is painful for human ears, recorded at approximately 188 decibels. Calls can be heard up to 600 miles away. This is useful for blue whales, because they are solitary animals, so they can communicate across vast distances.
The calls of male and female blue whales are different, though, with females only singing in single notes and males communicating in complex tunes.
How do blue whales reproduce?
Blue whales reach sexual maturity between six and 10 years old.
During the summer months, males will follow a female blue whale for several weeks, competing for their attention and initiating a race with other males if needed. They will also use calls to court females.
Calves are born at intervals of two or three years, with a gestational period of 12 months. When a whale is born, it is already seven metres in length – about the size of an elephant.
How long do blue whales live?
The life expectancy of a blue whale is similar to that of a human – about 80-90 years old. The oldest blue whale recorded was 110 years old.
Are blue whales endangered?
Blue whales are listed as endangered under the Endangered Species Act, and were once hunted to near extinction off Scotland’s coast.
Since commercial whaling bans, blue whales have become a protected species – but their recovery is slow, as it’s estimated that 99 per cent of the world’s population of blue whales was wiped out during whaling. Pre-whaling populations were about 350,000, but now there are only about 15,000 blue whales in the world’s oceans.
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The history of whaling in British waters
Whaling was once a vital industry, with whales hunted for their blubber (for oil and lamp fuel), baleen (whalebone – used for items such as corsets and umbrellas) and meat.
On the Isle of Harris in the Outer Hebrides, you can now see the remnants of Bunabhainneadar, one of Scotland’s last whaling stations. Opened in the early 1900s by a Norwegian company, the station was finally closed in the 1950s. The nearby isle of St Kilda was a regular haunt of blue whales.
Commercial whaling was banned in 1986 by the International Whaling Commission, in response to the overhunting of whales. This was a global ban, but in 2019, Japan withdrew from the IWC and resumed commercial whaling in its own waters.
Can blue whales be found in UK waters?
While they are rare, blue whales have been known to be found off the coast of the UK, particularly in the deep waters around the north and west of Scotland.
In 2015, a blue whale was spotted about 400km southwest of Cornwall. It may be the first footage of blue whales captured in English waters.
Why are they rarely seen in the UK?
Blue whales are rarely spotted in UK waters because their populations were severely depleted by commercial whaling operations over the last few centuries, but also because they prefer deep ocean habitats, further offshore.
When can you see them?
Sightings of blue whales are infrequent, but the best time to potentially spot them in UK waters – particularly in Scotland – is between May and October, and likelier still between July and September.
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Top image credit: Getty Images
