Post by University College Dublin

🇮🇪🦈 Almost half a century of sightings has revealed that Ireland’s waters remain an important seasonal refuge for the endangered basking shark, with new research identifying long-standing hotspots where the world’s second-largest fish returns year after year. Published in the journal Endangered Species Research, the research analysed 2,718 basking shark sightings recorded between 1978 and 2024 to investigate how the species uses Irish waters and the environmental conditions that influence its seasonal movements. The international study, involving researchers from University College Dublin and the Irish Basking Shark Group, found that basking sharks return to Irish waters. They are predictably seen each year around the Blasket Islands in County Kerry, the south coast of County Cork, and the Inishowen Peninsula and Malin Head in County Donegal. Sightings peak during the spring and summer months, likely reflecting seasonal peaks in the plankton they feed on. The results of our work suggest that, unlike in many other parts of the world, basking sharks continue to be present in Irish waters,” said lead author Dr Alexandra McInturf, PhD, Co-Coordinator of the Irish Basking Shark Group. “This bodes well for the status of their population in this area and also suggests that Ireland offers important habitat for this globally endangered species.” Dr McInturf added that the study would not have been possible without thousands of sightings submitted by members of the public. "This study relied heavily on data reported by members of the public to the Irish Whale and Dolphin Group and Irish Basking Shark Group, which really speaks to the power of including members of the public in research and conservation efforts." Basking sharks are the second-largest fish on Earth, growing to more than 11 metres in length. Despite their size, they feed almost exclusively on tiny plankton filtered from seawater and are harmless to humans. Following centuries of targeted hunting and more recent pressures including accidental capture in fishing gear, ship strikes and habitat degradation, the species is now classified as Endangered on the IUCN Red List. In addition to mapping where basking sharks occur, the researchers found that both the number of reported sightings and the size of shark groups have increased over time. "It's difficult to know what has driven the increasing number of basking shark sightings in Irish waters in recent years, but the increase may be due, at least in part, to natural phenomena such as a shift in key feeding areas used by basking sharks in the northeast Atlantic, or changes in other behaviours,” said Dr Ruth Leeney, UCD School of Biology and Environmental Science and Irish Basking Shark Group. The authors say protecting these seasonal hotspots could help safeguard important habitat for the globally endangered species and support future conservation efforts.