Shift in important areas for harbour porpoises

UK harbour porpoise populations are shifting to new areas, according to a new report that calls for further monitoring to help protect the species and ensure that marine conservation strategies are effective.

ORCA, one of the UK’s leading marine conservation charities, has launched its the State of European Cetaceans 2018 report after analysing data recorded by a network of hundreds of UK volunteers.

This year’s edition focuses on harbour porpoise populations around the UK, and highlights that the distribution of this species in the English Channel has shifted.

This could potentially have significant implications for efforts to protect a species that is facing an array of threats in Europe, with harbour porpoises one of the most threatened marine mammals in Europe due to their preference for coastal waters.

The report highlights that populations of these animals in both the North Sea and Celtic Sea have moved into the English Channel.

The cause for this shift is unconfirmed, but possible explanations include a shift in the harbour porpoises preferred prey or a change in sea conditions as a result of factors such as climate change.

ORCA director Sally Hamilton said: “These findings highlight both the important role that citizen scientists can play in protecting whales and dolphins, and how critical it is to continue to monitor these animals to better understand where they can be found and how their distribution is changing.

“Harbour porpoises are one of the most elusive species of cetacean, so it is a testament to the hard work and skill of our volunteers that we have been able to come to such profound conclusions from their efforts.”

Harbour porpoises are the smallest species of cetacean found around the UK, measuring 1.5m-1.7m long. They feed on small fish such as sand eels, and are identifiable from their distinctive triangular dorsal fin.

Harbour porpoises, like all cetaceans, are under threat from a broader array of threats than at any other point in history, with ORCA’s report discussing the impact of these on European marine wildlife.

The species is particularly vulnerable to being caught in fishing gear, otherwise known as bycatch, with 1,500 porpoises killed by UK fisheries in a year. Work to combat this and other threats is hampered by the limited nature of Government-funded monitoring programmes, which only take place once each decade.

Chris Packham, wildlife presenter, naturalist and ORCA patron, said: “A whale and dolphin census every ten years is not enough to keep tabs on an animal population that is, more than anything, a reflection of the ebb and flow of the oceans in which they live.

“ORCA’s real-time monitoring and reporting comprehensively fills in the other nine years and stops the Government from saying it can’t act in the interests of whale and dolphins when any sort of crisis affecting them occurs because it doesn’t have the evidence. This report is that evidence.”

Other threats profiled in the report include large whales being killed in collisions with ships, an issue that is widely underreported despite being one of the main threats facing larger species. ORCA have been working in partnership with Brittany Ferries to monitor fin whales in the Bay of Biscay and learn more about their interaction with large ships in one of the busiest shipping areas in the world.

Toxic chemicals such as polychlorinated biphenyls, or PCBs, are also identified a key threat, with recent research suggesting that orca populations in Europe are at critical risk of suffering a catastrophic population crash due to exposure to these pollutants.

“Threats to European cetaceans have never been greater, and without swift and decisive action we run the risk of losing some of these iconic and inspiring animals forever,” Ms Hamilton said. “The UK and other European governments need to create more safe spaces for our whales and dolphins in order to safeguard them for future generations.”

ORCA’s citizen scientists recorded data on over 13,500 cetaceans in 2017 alone, with 25 species observed during 85 surveys conducted from ferries and cruise ships.

ORCA’s The State of European Cetaceans 2018 report can be found in full at www.orcaweb.org.uk/soec