A highly pathogenic strain of avian influenza, H5N1, has swept through seal colonies along the UK coast, killing an estimated 75% of pups born this season. The outbreak, first detected in seabirds earlier this year, has now jumped to marine mammals, sparking fears of a broader ecological cascade. Fisheries Minister Mark Spencer has called for an emergency summit with leading virologists, ecologists, and climate scientists to assess the threat and coordinate a response.
Data from the UK Centre for Ecology & Hydrology show that since November, mortality rates among grey seal pups (Halichoerus grypus) have exceeded 70% in affected rookeries from Cornwall to Scotland. The virus, typically adapted to birds, has acquired mutations enabling mammal-to-mammal transmission, a worrying sign of evolutionary flexibility. “We are witnessing a real-time biological crisis,” said Dr. Helena Vance, Science & Climate Correspondent. “The combination of habitat stress from warming waters and a novel pathogen is a pressure many species cannot survive.”
The outbreak is concentrated in colonies that rely on fish stocks already depleted by overfishing and rising sea temperatures. Autopsies on infected pups reveal severe neurological and respiratory damage, consistent with systemic H5N1 infection. Biosecurity measures, including carcass removal and disinfection of beaches, have been implemented but are unlikely to contain the spread given the virus’s persistence in the environment.
This event is not an isolated incident. Similar die-offs have occurred in US sea lions and European harbour porpoises, prompting the World Organisation for Animal Health to issue a global alert. For seal populations already listed as vulnerable on the IUCN Red List, a 75% pup mortality rate could push them toward local extinction. The loss of these predators will trigger trophic cascades: overabundant prey fish may deplete zooplankton, altering carbon cycling and reducing the ocean’s capacity to absorb CO2.
Minister Spencer’s summit, scheduled for next week, will explore temporary culling of infected birds, vaccine development for wildlife, and stricter biosecurity at seal haul-out sites. But Dr. Vance cautions that such interventions address symptoms, not root causes. “Our reliance on industrial agriculture and fossil fuels creates the perfect storm for zoonotic spillover,” she said. “Every degree of warming expands the host range for pathogens. We are treating a fever while the planet burns.”
Conservation groups are calling for a moratorium on nearshore wind farm construction during pupping season, as noise and vibration may exacerbate stress. Meanwhile, the government faces pressure to fund a rapid-response wildlife disease surveillance network. The long-term solution, however, lies in reducing the drivers of ecosystem fragility: greenhouse gas emissions and biodiversity loss.
As the summit convenes, the clock ticks for the remaining seal pups. With spring warming accelerating, the window for containment narrows. “This is a test of our ability to manage a biosphere in collapse,” Dr. Vance concluded. “The seals are a canary in the coal mine, and we are ignoring the oxygen monitor.”
