Movements in the world of cetaceans


Cetacean populations and species are never static. But more evidence is showing the extent to which they are having to adapt and relocate.

Its perhaps not the most perfect analogy, but urban foxes in the UK only became a thing in the 1930’s, when the growing sprawl of garden-city suburbs encroached on their habitat. In true Darwinian style, they adapted and adopted (for good and bad) the city life. Cetaceans are no different - impacts on their habitat, whether positive or negative, may mean they need to decamp elsewhere. The reasons for this can be varied - the species on which they prey may have shifted, to colder or warmer climes having themselves been displaced. Some of the extraordinary sea temperatures we have seen over the past year will have made this an inevitability, and while some displacements will be temporary, we anticipate that many won't be.

So the effect of what we are now seeing more regularly on our surveys in the Northeast Atlantic is a greater diversity of species than at any point since records began. We had thought that perhaps this was possibly down to survey effort, since ORCA has been compiling a more authoritative and comprehensive set of data on sightings than has ever previously existed. But over the past couple of years we’ve begun to record more sightings of species that can only be described as uncommon in UK waters. Media reports indicate the same - with the recent rare sighting of a Sowerby’s beaked whale in shallow waters of the Welsh coast, increasing humpback sightings off the Cornish coast and (in more recent years) bowhead and northern bottlenose whales.

With this increased diversity of both species and cetacean groups moving into unfamiliar waters, so the risks increase, as they explore and investigate their new territories. Just this week, two common dolphins were sighted swimming up the River Ouse. A juvenile became stranded 40 miles inland and was sadly euthanized, and the adult was found dead a short while later.

One of the UK's worst ever strandings, of 55 pilot whales, took place in the Western Isles in July this year. While we know that strandings can be caused by multiple factors, unfamiliar stretches of water and the dangers that exist will be a risk to cetaceans while they reorientate and familiarize themselves with their new environments.

These ongoing disruptive factors represent a lengthy period of uncertainty for cetaceans, and one that is likely to be causing them stress as they adapt. The UK is highly fortunate to have the incredible network of volunteers that make up British Divers Marine Life Rescue (BDMLR), who mobilise to deal with strandings, whether actual or where cetaceans are at risk, in just about every corner of the UK coastline. Their work has saved the lives of so many stranded or injured animals, but they also have to deal with the frequent disappointment of being simply unable to help or where the animals they have tried to save cannot be rescued. Likewise the government-funded UK Cetacean Strandings Investigations Programme (CSIP) (and not just cetaceans but basking sharks and turtles) is on-call to record, study and inform a better understanding about why strandings occur and what can be done to mitigate against them.

You can also help - so many of the unusual and interesting sightings in the past decade have been land-based, meaning that a pair of binoculars and ORCAs’ OceanWatchers app can really help us gain a better understanding of what is happening in the oceans, and what that means for the incredible array of marine animals that live there.