Almost 5,000 dolphins, porpoises and whales have been found washed up dead on shores around the United Kingdom in a single seven-year period. Pictured, a mass stranding of long-finned pilot whales on a b

Almost 5,000 dolphins, porpoises and whales have been found washed up dead on shores around the United Kingdom in a single seven-year period. Pictured, a mass stranding of long-finned pilot whales on a b
It was an increase in strandings of 15 per cent on the previous seven-year period

The number of whales, dolphins and harbour porpoises washed up on UK shores has risen to just under 5,000 in the last decade, a study has found.

A total of 4,896 were were reported to have washed up on beaches between January 1 2011 and December 31 2017, the Government said.

It marks an increase in strandings of 15 per cent on the previous seven-year period, according to the research.

Of the 4,896 incidents, 4,311 were dead strandings, 186 were dead at sea including 21 entangled at sea, and 399 live strandings, only 132 of which were returned alive to the sea.


Causes of death

Post-mortem examinations on 1,030 of the animals revealed disease and being accidentally caught in fishing gear - also known as bycatch - were two of the most common causes of death.

The findings form part of a seven-year review published by the Government and led by the Zoological Society of London (ZSL), an international conservation charity.

Researchers recorded 21 different cetacean species - nearly a quarter of the total currently known to science - as well as six species of marine turtle and several species of large-bodied sharks.

They found 2017 had the highest number of strandings in a single year, with more than 1,000 recorded.

The team also looked into large-scale mass stranding events involving multiple animals, including one in July 2011 in the Kyle of Durness, Scotland, where 70 long-finned pilot whales stranded together.

According to the study, bycatch accounted for 23 per cent of common dolphin deaths and 14 per cent of harbour porpoise deaths.

Other deaths caused directly by humans included 25 animals killed by ship-strike and a single Cuvier's beaked whale that suffered a gastric impaction following the ingestion of marine litter.

Human links to deaths

Lead researcher and cetologist Rob Deaville said it was difficult to pinpoint the exact cause of the rise but that it could be linked to increased reporting and seasonal variation in species population.

"As both nets and propellers can cause characteristic injuries, we can readily diagnose causes of death which are directly related to human activity, such as bycatch and ship-strike," he said.

"However, the total proportion of deaths linked to the impact of humans is actually likely to be higher over the period covered by this report.

"For example, cases of infectious disease may be associated with exposure to chemical pollution, including legacy pollutants such as PCBs [polychlorinated biphenyls], which can have immunosuppressive effects."

New recordings

While the findings paint a largely "bleak picture", Mr Deaville said positives included the recording of 21 species - including the dwarf sperm whale - which had never previously been seen in the UK.

"It may be that, as the climate continues to change, the pattern of strandings around the UK may also change but we'll have to wait to see what future reports find," he added.

"That's the value of monitoring programmes. We produce long-term, continuous data that picks up changes in the UK's marine biodiversity that other approaches might miss.

"By investigating stranded cetaceans, we can also gain a real insight into the wider health of the marine environment and the frankly extraordinary wildlife that can be found around our shores."