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, reports Plymouth University.

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. Researchers report that as a result of their ongoing work they estimate the pod currently consists of just 48 individual dolphins.

Photo: Anabelle Lowe

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 pollution and fishing pressure.

Associate Professor of Marine Conservation at the University of Plymouth, Dr Simon Ingram, leads the bottlenose dolphin research project. He said because dolphins mainly go unseen, people failed to appreciate how vulnerable they were. “This population lives along one of the most developed and busy coastlines in the world which poses a clear threat to their conservation,” he said. “To see the south coast population decline to extinction would be a local tragedy for the dolphins and for us.”

Citizen science network

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.

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.

The full news release from Plymouth University can be read here. The research study ‘Using citizen science data to assess the vulnerability of bottlenose dolphins to human impacts along England’s south coast’ is published in Animal Conservation and can be found here.