England's only resident population of bottlenose dolphins is under serious threat from a combination of human activity, environmental pollution and difficulties in rearing young that survive into adulthood, according to new research.
For almost a decade, scientists and conservation groups based along the English Channel coast have been working together with citizen scientists to monitor the movements and distribution of this population.
This has enabled them to establish the most detailed picture yet of this population, their movements and social interactions, and the challenges they face on a daily basis.
Writing in the journal Animal Conservation, the researchers report that as a result of their ongoing research they estimate the pod currently consists of just 48 individual dolphins.
That is less than half the size of most coastal bottlenose dolphin populations, and around 10 times smaller than a pod known to inhabit the Channel coast of France.
Their fight for survival is made even more challenging by the fact they inhabit some of the busiest shipping lanes in the world and also coastal waters known to suffer from repeated and prolonged spells of pollution and fishing pressure.
These findings have led the researchers to call for urgent measures to protect the population and its habitats, or risk the possibility that this group of animals may not survive.
The ongoing research is being led by Cornwall Wildlife Trust and scientists at the University of Plymouth, who have been having working with a range of partners along the Channel coast over a number of years to collate and analyse sightings data, through the South Coast Bottlenose Dolphin Consortium.
This particular study is the result of work by former Marine Biology MRes student Shauna Corr, and former MSc Marine Conservation students Rebecca Dudley and Saskia Duncan, supervised by Associate Professor of Marine Conservation Dr Simon Ingram.
Dr Ingram, who leads the bottlenose dolphin research project and is senior author on the study, said: "Bottlenose dolphins are highly intelligent and social animals with complex cultures. They are known to have some of the closest interactions with humans of any species on the planet, but because they live in the sea, and not on land, they go unseen by most people and we fail to appreciate quite how amazing yet vulnerable they are. This population lives along one of the most developed and busy coastlines in the world which poses a clear threat to their conservation. To see the south coast population decline to extinction would be a local tragedy for the dolphins and for us."
This population of bottlenose dolphins was first documented by scientists in the mid-1990s and became the subject of detailed scientific analysis again in 2017 due to concerns raised by Cornwall Wildlife Trust about their plight and vulnerability to human impacts.
Individual bottlenose dolphins can be identified from their unique fin markings enabling scientists to build up a catalogue of known dolphins which, through repeated sightings, enabled the MSc students to track the movements of individual dolphins over several years.
To achieve this, a citizen science network of boat owners, ecotour operators and members of the public was established along the length of the south coast from Cornwall to Sussex to pool sightings from the entire coast.
As a result of the South Coast Bottlenose Dolphin Consortium was formed and to date has yielded almost 7,500 sighting reports generated between 2000 and 2019.
These repeat sightings revealed that dolphins from this pod travel the coast between North Cornwall and East Sussex, with some individuals known to have travelled up to 760km between sightings.
The population appears to be isolated with individuals known to socialise within their own pod close to the shore but not with others from other populations normally found in the open sea.
The study's authors hope this information will be used by statutory marine conservation organisations to provide better protection for this highly vulnerable population and to take appropriate measures in order for the pod to survive.
Shauna Corr added: "Conservation measures to protect these animals have previously been hindered by a lack of knowledge of population size, distribution, and ranging behaviour. Thanks to a citizen science network stretching right along the English Channel and beyond, we can now fill these knowledge gaps. By highlighting the most damaging human activities, and regions of conservation significance, our results will be useful for developing management policies for threat mitigation and population conservation, to protect this vulnerable group."
About the University of Plymouth
The University of Plymouth is renowned worldwide for its high-quality research, teaching and innovation. With a mission to Advance Knowledge and Transform Lives, the University drives the global debate in disciplines from marine and maritime to medicine, law, computing and climate action.
With a city centre campus and further state-of-the-art facilities spread across Plymouth and beyond, plus Devon and Cornwall's stunning coast and countryside on the doorstep, the University provides a unique blend of urban and outdoor lifestyle opportunities for everyone who studies and works here. A three-time winner of the Queen's Anniversary Prize for Higher and Further Education – most recently in respect of its pioneering research on microplastics pollution in the ocean – Plymouth consistently ranks among the world's leading universities for its innovation, research and teaching in relation to the United Nations' Sustainable Development Goals.
Plymouth's teaching and learning excellence is reflected in one of the highest numbers of National Teaching Fellows of any UK university. With over 18,000 undergraduate and postgraduate students, plus a further 7,000 studying at partner institutions in the UK and around the world, and over 175,000 alumni pursuing their chosen careers internationally, the University of Plymouth has a growing global presence.
About Cornwall Wildlife Trust
Cornwall Wildlife Trust has been protecting Cornwall's wildlife, on land and at sea, since 1962. It is Cornwall's leading local wildlife conservation charity, with over 17,000 members and 1,000 volunteers. The charity manages 59 nature reserves across Cornwall, including a range of habitats such as woodlands, meadows, wetlands and heaths. It also runs a number of marine and terrestrial based conservation projects in partnership with others, including Upstream Thinking and Penwith Landscape Partnership, and hosts the Environmental Records Centre for Cornwall and the Isles of Scilly (ERCCIS).
The Trust is one of 46 in the UK. Together, they make up the Royal Society of Wildlife Trusts. Visit http://www.cornwallwildlifetrust.org.uk and follow @cwallwildlife on Twitter or Cornwall Wildlife Trust on Facebook, Instagram and LinkedIn to keep up-to-date with Trust's projects, events and news.
The South Coast Bottlenose Dolphin Consortium
The South Coast Bottlenose Dolphin Consortium was instigated by Cornwall Wildlife Trust in 2017 and is a partnership of various stakeholders throughout the southwest of England sharing a common interest in developing understanding and conservation of the region's bottlenose dolphins. The Consortium collates records and photos of bottlenose dolphin encounters from the public to build on previous research, with reports coming from ferries, marine tour operators, charitable organisations, land-based observers and other interested parties.
