ZSL’s “CSI of the Sea” team asks British public to report seal mortalities to protect iconic species

This International Day of the Seal (March 22), the British public are being urged to report strandings of dead seals across English and Welsh coastlines and waterways to help ZSL scientists further understand the threats facing marine mammals on our native shores.  

Behind the call is the ZSL-led Cetacean Stranding Investigation Programme (CSIP), which through its 30-year investigation into the whales, dolphins, porpoises, marine turtles and sharks that strand around the English and Welsh coast – including the smalltooth sand tiger shark stranded in Hampshire this weekend - already holds one of the world’s largest data sets on threats to these marine species. 

Now, with additional funding secured from Defra, the team will be able to expand their essential research to provide much-needed insight into the health of the two seal species found in UK waters - harbour and grey seals – but only with the public’s help.  

CSIP Project Manager and researcher at ZSL’s Institute of Zoology Rob Deaville explained: “We know that dead seals are sadly routinely found on beaches around England and Wales, but without coordinated research, we simply don’t yet have a strong understanding of what is causing their deaths – or even on how many are dying every year – which presents a challenge to taking the right evidence-driven conservation action where any mortality may be due to human activities.  

“Seals are keystone species, meaning that they play a crucial role maintaining biodiversity within their ecosystem, so any threats to them will have a knock-on effect on the marine animals they live alongside. 

“We know from decades of investigating cetacean strandings that the reasons behind these events can be varied and complex. Expanding our remit into seal mortality too will help us build a detailed picture of the pressures that seals in UK waters are facing and how we can protect the future of these essential species. 

“After 30 years of CSIP investigating cetacean strandings in the UK, members of the public already know to call us when they see a dolphin or whale sadly washed ashore - now we’re asking people to do the same and inform us of any dead seals they spot along our coastlines and waterways.” 

CSIP’s investigation into seal mortalities comes over 20 years after the last large-scale systematic investigation into seal deaths in the England and Wales, when in 2002 the fatal disease phocine distemper virus (PDV) is estimated to have halved seal populations in the North Sea. While over 4,300 incidences of dead seals were recorded in the UK during that year, there has been limited funding for long-term seal mortality investigation in the years since – drastically limiting the research needed for scientists and conservationists to understand the threats that these animals face. 

Rob continues: “Monitoring seal populations and mortality is essential to allow us to spot any future outbreaks of PDV or other diseases such as influenza or mouth rot at an early stage. In light of recent positive cases of avian flu found in UK seals, we need to gain a better understanding of this new and emerging issue.  

“We also need to learn more about the impacts on these iconic mammals from human activities, such as entanglement in fishing gear or marine plastics, ship-strikes, shooting and climate change. Investigating seal mortality may also help us gain a better understanding of the scale and extent of interactions between grey seals and other marine mammals.” 

This much-needed expansion of CSIP’s work has been made possible by an eight-year grant from Defra, and will be co-ordinated with partner organisations including the Cornwall Marine Pathology Team, Natural History Museum, Marine Environmental Monitoring and the Cornwall Wildlife Trust Marine Strandings Network. 

Between CSIP’s inception in 1990 and 2020, thanks to call-ins from members of the public, the ZSL-led team has recorded data on nearly 18,000 cetacean strandings in the UK, carrying out over 4,500 post-mortem examinations while maintaining an internationally important tissue archive from a wide range of vulnerable marine species.   

ZSL-led CSIP research has directly contributed to measures being taken to reduce unstainable cetacean by-catch in fisheries and an EU-wide ban on dangerously polluting chemicals, as well as helping to discover a decompression sickness like condition in cetaceans.   

ZSL CEO Matthew Gould added: “Seals are an essential part of the UK’s marine ecosystem.  Like too many other species, they are under threat.  ZSL is a science-driven conservation charity, and I’m delighted that our CSIP programme has been recognised with this important grant from Defra.  It will allow our scientists to do even more to protect the UK’s species and restore its ecosystems.” 

Seal mortality sightings in England and Wales can be reported to the CSIP by calling 0800 652 0333. It is important that members of the public do not approach or touch any dead seals spotted due to the risk of them carrying disease.