There has been an increase in sightings of female sperm whales around the Irish coast, a development that could be tied with climate change, reveals a new research study. The study, which is based on records of stranded female, juvenile, and calf sperm whales in Ireland, is investigating the seemingly rising trend of female strands in the area. The research suggests that the pattern of female strandings could imply a dynamic shift in the population structure in Ireland from predominantly male to a mix that includes female groups.
The Marine and Freshwater Research Centre’s Seán O’Callaghan, from the Atlantic Technological University in Galway, cautioned that the precise influence of climate change on offshore Irish waters in the coming years is yet uncertain. He, however, averred that the increasing visibility of female sperm whales could signify a vast change in the habitat for the species, influencing other apex predator communities as well.
The study confirmed an increased presence of female, juvenile and calf sperm whales in the waters off the Ireland coast at latitudes higher than the traditional nursery grounds in the northeast Atlantic. The findings relied upon both historical and modern data collated from whaling, strandings, and sighting records from 1910 through to 2023.
The analysis indicated a population transformation over the last decade in the waters off Ireland. Formerly, the population was primarily male, but the change includes increasing frequencies of females, as evinced by strandings and sighting records.
Furthermore, the research underscored that marine heatwaves have become an alarming global issue. These heatwaves penetrate deep into the sea and could impact up to depths of 200m. Their effects tend to intensify with depth and persist for longer durations.
Sea surface temperatures around Ireland saw a surge during a warm spell from the mid-1990s to mid-2000s, reaching a peak in 2007. During this period, Irish waters were hotter by an average of 0.8 degrees compared to the years from 1960 to 1990.