Biodiversity beneath the waves: 24 cetaceans of Scotland
A quarter of the global cetacean (the collective for whale dolphin and porpoises) species have been recorded in Scotland’s seas, marking this as an important area for these creatures.
Some are resident and call our shores home, while others are mysterious visitors, only known through stranding records. Some species are commonly recorded, while others have only been reported a handful of times since records began. From the wee harbour porpoise to the largest animal which has ever graced the earth, here are the 24 species recorded in Scotland’s seas.
HARBOUR PORPOISE
Harbour porpoises are the UK’s smallest cetacean and can be seen all year round in the Hebrides – they are our most commonly reported species. A Special Area of Conservation (SAC) for the harbour porpoise was designated off Scotland’s west coast – the largest for the species in Europe. HWDT data was instrumental in demonstrating how important the Hebrides are for porpoise and in setting the boundary of the SAC.
COMMON DOLPHIN
Common Dolphins can be found in small pods of just 2 individuals, but where good feeding is available, can congregate in groups numbering into the thousand. The sightings rate of common dolphins has increased significantly over the decades HWDT has been monitoring Hebridean seas. Once a rare summer visitor, in recent years they have been reported every month of the year. Theories for this include rising sea temperatures, species range shift, food availability, and population increase; however understanding the drivers of change is complex and likely a combination of factors.
Minke whale
Minke whales migrate to feed in the productive waters off the west coast of Scotland. They are frequently seen in coastal waters between April and October, and can occasionally be seen during the winter months too. Their migration patterns are not fully understood. Our minke whale catalogue shows that more than 300 individual whales have been identified in the Hebrides since 1990. A third (33%) have been seen more than once – some over many years and others numerous times.
Knobble is the most frequently seen animal our catalogue, recorded most years for two decades in the waters around Mull. This photo was taken by Andy Tait who knows Knobble well - this encounter was during a trip with Sea Life Mull in 2024.
ATLANTIC WHITE-SIDED DOLPHIN
Atlantic white-sided dolphins are often confused with common dolphins due to the yellow colouration on their sides. Confirmed records of the species in the Hebrides are quite rare and when they are reported it is usually around the Outer Isles. A pod was reported in Stornoway Harbour in August 2021 and subsequently stranded, apparently due to a sick individual. However, the pod refloated and made their way out of the harbour and into deeper waters.
WHITE BEAKED DOLPHIN
White-beaked dolphins live in the waters around the Hebrides year-round. They have a preference for colder water and are most often seen around the Outer Hebrides. Sightings in recent years may suggest that white beaked dolphins are moving further north, potentially due to rising sea temperatures or changes in prey availability. A similar northwards species shift has been seen in common dolphins, which could be leading to competition between the two delphinid species over resources.
RISSO’S DOLPHIN
Risso’s Dolphins are large, distinctive dolphins and are found in Hebridean waters all year round. The seas off the east coast of the Isle of Lewis are a Marine Protected Area, designated for the Risso’s dolphin. Individuals have been re-sighted year on year in the area, indicating at least partial residency for some dolphins. Mothers with calves and groups consisting entirely of juveniles have also been recorded within the MPA. This suggests these waters are not only essential for feeding but may also be important for breeding, nursing and raising their young.
BOTTLENOSE DOLPHIN
Scottish bottlenose dolphins are the largest in the world reaching a whopping 4 metres, allowing them to live in our cool water year-round. A coastal species, the Hebrides has two distinct pods of bottlenose dolphins: the Barra Boys, and the Inner Hebrides Pod. The Barra Boys (which does contain females!) are found almost exclusively around the Isles of Barra and South Uist and consists of up to 20 individuals; the Inner Isles pod ranges from Skye to the Isle of Arran and contains around 30 - 40 individuals.
KILLER WHALE
There are three populations of killer whale recorded in Scotland’s seas: the West Coast Community, the Northern Isles Community and a mysterious group which have been recorded off Scotland and Norway – potentially part of an offshore population which comes closer inshore to feed occasionally. Individuals and pods from the Northern Isles Community travel between Scotland and Iceland, while the West Coast Community is exclusive to the UK and Ireland, with no sightings recorded elsewhere. In recent years, only two old bulls from the West Coast Community have been recorded: John Coe (left) and Aquarius (right).
HUMPBACK WHALE
Individual humpback whales can be identified by the unique pattern on the underside of their tail or fluke. In Scotland, citizen scientists have helped deepen the understanding of humpback in our seas, by recording and identifying individuals. There are now more than 100 humpbacks in the Scottish Humpback Catalogue. In recent years, the sightings rate of humpback whales has increased in Scottish seas, but the reasons behind this are unknown. We do know that global humpback populations have rebounded since the Monitorium on commercial whaling in the 80’s. Perhaps the humpback whales we’re spotting in Scottish seas now are a result of that key decision to halt an inhumane, unsustainable and unnecessary industry.
FIN WHALE
Fin whales are the second largest cetacean in the world after the blue whale, growing up to an incredible 27 metres. The fastest of the great whales, fin whales can travel up to 90 miles a day, reaching speeds of 25mph. Fin whales are shallow surfacers and, unlike other large whales, will not raise their tail fluke in the air when diving. Off Scotland’s west coast, fin whales are quite rare and are usually seen in the summer months, taking advantage of the good feeding available during their migration.
SEI WHALE
Sei whales are the third largest whale species in the world. Sei whales can be identified by their distinctive surfacing pattern – like a submarine rising above the waves, as opposed to a rolling back. Sei whales are quite a rare sight, although there were a number of sightings reported during 2023 season around Lewis and Harris and, in 2024, reports were received off the east coast.
SPERM WHALE
The Sperm Whale is the largest of the toothed whales. In the Hebrides, sightings are usually of solitary animals. Sperm whales are reported a handful of times each year off Scotland’s west coast. Unfortunately it’s not always a good sign when this species is found inshore. In November 2019, a teenage sperm whale stranded on Luskentyre Beach on the Isle of Harris. It had 100kg of plastic in its stomach, although it couldn’t be concluded that this was the principle cause of death.
NORTHERN BOTTLENOSE WHALE
Northern bottlenose whales are a deep diving species of beaked whale. They are very elusive leading us to know very little about their behaviour and movements. Data collected by HWDT’s Whale Track sightings community 2019-2023 shows a predictable occurrence of northern bottlenose whale sightings in Scottish inshore waters in late summer and early autumn. Northern bottlenose whales move on to the continental shelf from deeper oceanic waters, mainly between July and October. The same trend is shown in historical whaling records and strandings data.
PILOT WHALE
Long-finned pilot whale are a large species of dolphin and are highly social animals, forming tight-knit pods. Pilot whales are prone to mass strandings, which could in part be due to their strong social bonds. Investigations into mass stranding events often point to one individual getting into trouble and stranding, leading to the rest of the pod to follow them ashore. There have been several of this mass stranding events along Scotland's coast. In 2023, 55 animals which stranding on the Isle of Lewis. Last year, a pod of 77 stranded on Orkney’s coast.
CUVIER’S BEAKED WHALE
Cuvier’s beaked whales are rarely seen alive in coastal waters — most of what we know about them comes from strandings. They hold the record as the deepest diving mammal on Earth, plunging to depths of over 3,500 metres in search of squid, and staying underwater for an astonishing 3 hours and 45 minutes.
In January 2019, one live-stranded in Calgary Bay on the Isle of Mull. The year before, an unusual mortality event unfolded across Scotland and Ireland, with over 90 beaked whales washing ashore during August and September 2018. The suspected cause? Military sonar, which can disorient these deep-diving specialists. This event deeply affected artist Mhairi Killin, who discovered one of the whales on her local beach on the Isle of Iona. It inspired her to create On Sonorous Seas, an artistic response to understand the militarisation of our seas and the impact this human activity has on the denizens of the deep.
From initial analysis undertaken by SMASS, the mature male whale which stranded on Calgary Bay seems to have died of natural causes.
Rarer Records
Scottish whaling records show blue whales were once found off our shores
BLUE WHALE
Blue whales are the largest animal in the world and are a cosmopolitan species, found in all the world’s oceans. Historically, the waters around Scotland would have been an important habitat for blue whales. Unfortunately, they were hunted extensively with an estimated 501 landed in Scottish waters between 1904 – 1951. Since hunting ended in 1951, very few blue whales have been seen in Scottish waters. Dr Conor Ryan published some fascinating research, diving into historic whaling records to explore the species that inhabited our seas in years gone by.
BELUGA
Belugas are an Artic whale species and one of the most recognisable because of their white colour and prominent, bulbous melon which they can move around to create various whistles, clicks, and squeals. They are highly social animals usually in groups of around 15 but can congregate in loose groups of 1000s when on migration.
There have been only a handful of confirmed sightings of beluga whales in Scotland. The most recent was Monday 20th May 2025 in Loch Broom! The footage below was captured by Noel Hawkins of Shearwater Cruises. Prior to that belugas were last seen in the Hebrides in April 1995, off Applecross in Loch Duich. A beluga was recorded off Shetland in 2024.
SOWERBY’S BEAKED WHALE
Sowerby’s beaked whales are named after John Sowerby - an English naturalist and artist who first described the species in 1804 from a skull obtained from a male that had stranded in the Moray Firth, Scotland, in 1800. As with many other species of beaked whale, most of what we know about them comes from stranded individuals. They are one of the most commonly stranded species of beaked whale with more the 40 reported stranding events in Scotland since 1989. Most of these strandings have been on the west coast, especially the Western Isles. This is likely linked to the proximity of the continental shelf edge.
TRUE’S BEAKED WHALE
True’s beaked whales are incredibly rare and have only been identified at sea a handful of times. In 2020, a female washed up in Kearvaig Bay in in Sutherland. Strandings of beaked whales are rare but can teach us a lot about species that are otherwise hard to study. The skeleton of the individual which stranded in Sutherland is now held by National Museums Scotland.
NORTH ATLANTIC RIGHT WHALE
The North Atlantic right whale is a large, finless, baleen whale which is known for its inquisitive nature, a trait which makes it easy to identify and, unfortunately, an easy to target for whalers. In Scotland, where they were once a common sight, they were hunted to near extinction until protections were enforced in 1934. It is reported, though, that Norwegian whalers hunting in Scotland considered them to be incredibly rare by 1906. There have been no recent sightings of right whales in Scotland with the last known occurring in 1980, west of the Outer Hebrides, and then north of Shetland in 2000. In 2024, a potential sighting of a Northern Atlantic right whale in Irish waters sparked great excitement.
FALSE KILLER WHALE
False killer whales have been recorded in oceans all around the world although little is known about the true extent of their distribution as most information about this species comes from stranded animals. The only confirmed false killer whales in Scotland came in the form of a mass stranding event in October 1927. Over the course of a week, around 150 false killer whales stranded in Dornoch Firth on the east coast of Scotland.
Stranded ‘caaing false killer whales’ of 147 washed up on the shore of Dornoch Firth 1927 ©Historylinksarchive
STRIPED DOLPHIN
Striped dolphins are an offshore species found in temperate and tropical waters. In Scottish waters they are usually seen in small groups although in their normal range they can be seen in offshore groups of 100s. They are occasionally seen in the Hebrides usually only in the summer months, the most recent confirmed sighting (with a photograph to confirm species) was reported to HWDT via Whale Track at Loch Na Keal, Isle of Mull in August 2021.
A beautiful capture of a striped dolphin in Loch na Keal, by Whale Tracker, peter-starling-1
FRASER’S DOLPHIN
Fraser’s dolphins are a deep water, tropical species. The only record of a Fraser’s dolphin in the Hebrides was in 1996, when a freshly dead individual was discovered on South Uist. The dolphin couldn’t immediately be identified so the skeleton was collected and comparisons to other specimens as well as the colour pattern led to it being a identified as a male Fraser’s Dolphin.
PYGMY SPERM WHALE
Pygmy sperm whales are a very rarely sighted cetacean and most information about them comes from strandings. Like the name suggests they look like sperm whales but only grow to about 3.5 metres. Pygmy sperm whales have a unique ability to release an ink-like substance that is stored in their intestine when they feel threatened, similar to a squid’s threat response. They can release up to 3 gallons of a dark reddish-brown liquid in order to escape from perceived threats and predators. A pygmy sperm whale live stranded on the Isle of Seil - our Science Officer at the time, Dr Nienke van Geel, attended. The whale sadly died but its skeleton is preserved at the National Museum of Scotland in Edinburgh.
Scotland's seas boost an extraordinary array of marine life, with 24 species of whales, dolphins, and porpoises recorded in its waters. From the elusive beaked whale to the ocean’s apex predator, the killer whale, these cetaceans contribute to the rich tapestry of biodiversity that defines our marine ecosystems.
Understanding and protecting these species requires collective effort. By reporting your sightings through our free Whale Track app, you become an integral part of a community-driven initiative that enhances our knowledge and informs conservation strategies. Whether you're a local resident, a seafarer, or a visitor, your observations can help safeguard the future of these remarkable creatures and the vibrant seas they inhabit.