Imagine you‘re sat on the coast, several metres above the water. The strong cliff wind blows your hair in all directions, while the flight of gulls and fulmars livens up the sky. A kestrel hunts just within your field of vision, diving down towards a hidden stretch of land below you, its eyes locked onto a small mammal scrambing around in the undergrowth. The sea dominates your vision, stretching for miles and miles, as far as your eyes can see.
You are reluctant to part your gaze from the surface. Scouting, waiting. Then you see it: a rising column of water vapour, soon bent by the wind, and a massive dark figure that follows before retreating underwater. People are cheering all around you. They point their fingers and their binoculars to the spot, nudge their neighbours to keep looking, while frantically shouting: Whale! Whale!’
Humpback whale sightings have become an attraction for nature enthusiasts across the country as people rejoice in witnessing their puffs and breaches. Whales were once a rare visitor to British waters, but their presence has become more common in recent years, with increased sightings reported across the country. Yet, as happy as we are for their increasing visits, it is impossible not to wonder why we are seeing this trend. Should we be celebrating an indication that whale populations are successfully recovering, or exercising caution as to whether these appearances are a call for help?
Following a noticeable increase in humpback sightings in Scotland’s Firth of Forth between 2017 and 2018, a small team of researchers published a study in 2019 examining confirmed sightings and exploring several possible explanations for the growing presence of whales along the UK coastline.
Range reoccupation
One theory points to population recovery after the end of large-scale commercial whaling.
Countless animals have fallen prey to commercial whaling vessels over the years as they lurked along migration routes and feeding grounds, targeting whales at their most predictable and vulnerable moments. In the 20th century alone, nearly 2.9 million whales were killed globally for their meat and blubber.1
Commercial whaling in the North Atlantic effectively ended in 1986, when the International Whaling Commission’s global moratorium on commercial whaling came into force. Since then, some humpback whale populations have shown encouraging signs of recovery.
In the North Atlantic, humpback whales (Megaptera novaeangliae) undertake long annual migrations between northern feeding grounds and southern breeding areas. During summer, they feed in highly productive waters around Iceland, Greenland, Norway and parts of the North Sea. As winter approaches, they travel thousands of kilometres south to breed in warmer regions such as the West Indies and the waters around Cape Verde.
As populations grow, ecological theory suggests that individuals may begin to expand beyond their core habitats.
Known as the dispersion hypothesis, this idea proposes that younger or less dominant whales move into new, or previously abandoned, areas to reduce competition for food.
Increasing sightings around the UK could, therefore, reflect the gradual rediscovering of waters that were once part of the wider migratory landscape for Humpback whales before industrial whaling dramatically reduced their numbers.
Cathy Gibbon’s from Queen’s University Belfast is looking into this using whale song, which can be detected along the migratory route. The hope is that audio records could help to get a better picture of how many whales are using the waters around the UK and whether locations in Northern Scotland and Northern Ireland are acting as migratory feeding stations.2
Shifting prey patterns
Climate change is also altering the distribution and seasonal timing of many marine species across the North Atlantic. Long-term monitoring programmes, such as the Continuous Plankton Recorder Survey have shown that plankton communities have shifted significantly in response to warming seas.3 These changes can ripple up the food chain, affecting the distribution of small fish and zooplankton such as krill – the main prey for humpback whales.
Because humpback whales closely track areas where food becomes concentrated, shifts in prey distribution may influence where whales choose to forage during their migrations.4 If prey species such as Atlantic herring, sandeels or krill are becoming seasonally abundant in parts of the North Sea or along the UK coastline, migrating humpbacks may increasingly stop to feed as they pass through. In this way, climate-driven changes in ocean ecosystems could help explain the recent rise in humpback whale sightings around the UK.
Human connection to nature
Another possible explanation for the rise in humpback whale sightings is not necessarily an increase in whales at all, but an increase in people looking for them.
In recent decades, citizen science projects and public reporting networks have greatly expanded the monitoring of marine wildlife around the UK. Organisations such as the Sea Watch Foundation encourage members of the public to record sightings of whales, dolphins and porpoises, creating large datasets that help scientists track cetacean distribution. At the same time, whale-watching tourism, improved camera technology and the rapid spread of information through social media mean that unusual encounters are now far more likely to be photographed, shared and logged than they were just a few decades ago.
This increased observation effort can influence how frequently whales appear in the scientific record. In other words, if more people are watching the sea and reporting what they see, whales that might once have gone unnoticed are now being documented. While this does not mean the whales are not returning, it highlights an important challenge for researchers: distinguishing real ecological changes from improvements in how we observe and record the natural world.
Ecological importance
But, regardless of why whales are returning, their reappearance raises another important question: what does their presence mean for the wider marine ecosystem?
Whales are often described as ecosystem engineers – species that actively shape the environments around them. Far from being mere passengers in the ocean, they influence how nutrients move, where productivity occurs, and ultimately which organisms can thrive.5
One of the most remarkable ways they do this is through nutrient cycling. We only see Humpback whales feeding at the surface, but most of their feeding time is actually spent deep underwater. By feeding on animals at depth, and pooping it back out at the surface, they are effectively fertilising the upper layers of the ocean.6 This process, sometimes referred to as the ‘whale pump,’ transports essential elements such as nitrogen and iron from deeper waters into the sunlit zone where microscopic plants, known as phytoplankton, grow.
Phytoplankton may be tiny, but their importance is immense. They form the foundation of marine food webs, supporting everything from krill and small fish to seabirds and large predators. Through photosynthesis, they also absorb vast amounts of carbon dioxide and produce a significant proportion of the oxygen we breathe.
By fertilising phytoplankton, whales indirectly enhance ocean productivity. More phytoplankton can mean more zooplankton such as krill, which in turn support fish stocks and larger marine animals. In this way, whales help sustain the very prey populations they rely on.
Even in death, their bodies continue to nourish the ocean, sinking to the seafloor and creating “whale falls” that provide a bountiful meal to deep-sea dwellers!
This means their presence in British waters has the potential to bring back ecosystem processes that were heavily disrupted by centuries of industrial whaling, creating a healthier sea in a time when saving our marine ecosystems is more important than ever.
Although these theories are emerging around the return of Humpback whales, to better understand the forces that are shaping the movements of Humpback whales, continued research and careful long-term monitoring is required.
What is clear, however, is that whales play a vital role in the health of marine ecosystems. Through their feeding, migration and nutrient cycling, they help support the productivity of the ocean and the countless species that depend on it.
If these giants are returning more often to British waters, their presence could assist the gradual restoration of ecological processes that were heavily disrupted during the era of industrial whaling, providing a reminder that marine ecosystems can recover when given the chance.
Want to learn more about whales and how you can get involved?
- Citizen science – share your Humpback whale sightings on Happywhale to help monitor whale activity and contribute to ongoing research.
- Information – The Whale and Dolphin Charity (WDC) offer some great articles and information on why whales are important, the threats they are facing, and how you can get involved with their campaigns. –https://uk.whales.org/create-healthy-seas/climate-change/
- Report – For more in depth reading, they have published a report on how whales help fight climate change, with section four (pg.28) going into more detail on the Whale Pump. – https://uk.whales.org/wp-content/uploads/sites/6/2023/12/whales-in-hot-water-climate-change-report-2023.pdf
- Book – Fathoms: The World in the Whale by Rebecca Giggs – ‘When writer Rebecca Giggs encountered a humpback whale stranded on her local beachfront in Australia, she began to wonder how the lives of whales shed light on the condition of our seas. Fathoms: The World in the Whale blends natural history, philosophy, and science to explore: How do whales experience ecological change? Will our connection to these storied animals be transformed by technology? What can observing whales teach us about the complexity, splendour, and fragility of life? In Fathoms, we learn about whales so rare they have never been named, whale songs that sweep across hemispheres in annual waves of popularity, and whales that have modified the chemical composition of our planet’s atmosphere. We travel to Japan to board the ships that hunt whales and delve into the deepest seas to discover the plastic pollution now pervading the whale’s undersea environment.’
Article written by Maria Giulia Checchi and edited by Nia Clarke
Primary paper:
O’Neil, K.E., Cunningham, E.G. and Moore, D.M. (2019) ‘Sudden seasonal occurrence of humpback whales megaptera novaeangliae in the firth of forth, Scotland and first confirmed movement between high-latitude feeding grounds and United Kingdom Waters’, Marine Biodiversity Records, 12(1). doi:10.1186/s41200-019-0172-7.
Other references:
Rocha, Jr., R.C., Clapham, P.J. and Ivashchenko, Y. (2015) ‘Emptying the oceans: A summary of industrial whaling catches in the 20th century’, Marine Fisheries Review, 76(4), pp. 37–48. doi:10.7755/mfr.76.4.3.
Humpback whales migrate through UK waters (no date) Humpback whales migrate through UK Waters | Agri-Food and Biosciences Institute. Available at: https://www.afbini.gov.uk/news/humpback-whales-migrate-through-uk-waters (Accessed: 10 March 2026).
Ostle, C. et al. (2022) ‘Multidecadal changes in biology influence the variability of the North Atlantic Carbon Sink’, Environmental Research Letters, 17(11), p. 114056. doi:10.1088/1748-9326/ac9ecf.
- Belanger, Michael & Askin, Nesime. (2018). Humpback Whale Expansion and Climate Change- Evidence of Foraging Into New Habitats. 9. Available at: https://www.researchgate.net/publication/324950395_Humpback_Whale_Expansion_and_Climate_Change-_Evidence_of_Foraging_Into_New_Habitats
Roman, J. et al. (2014) ‘Whales as marine ecosystem engineers’, Frontiers in Ecology and the Environment, 12(7), pp. 377–385. doi:10.1890/130220.
Blennd (2023) The whale pump: Why is poop so important for the planet?, SeaLegacy. Available at: https://sealegacy.org/the-whale-pump-why-is-poop-so-important-for-the-planet/ (Accessed: 11 March 2026).
