Hebrides Experiences Record Sightings of Minke Whales in 2023 but Decline in Basking Sharks, According to New Report
Wednesday 25 September, 2024 – Scotland’s nature agency NatureScot has published a new report by the Hebridean Whale and Dolphin Trust, revealing the highest sighting rates and numbers of minke whales ever recorded in the Hebrides in 2023. However, the report also highlights the lowest known sightings for basking sharks in the same region.
The report presents research findings collected during the Trust’s marine expeditions onboard its research vessel, Silurian, over the past three years. It also includes data from the past twenty years of the Trust’s monitoring program.
The latest findings suggest changes in sighting rates for minke whales and basking sharks, with a possible connection between the two species. The Trust notes that when sighting rates for basking sharks are high, they are low for minke whales, and vice versa. The reasons for this phenomenon are yet to be explained, and the Trust plans to conduct further research to analyze the trends and investigate potential causes, such as climate change.
Dr Lauren Hartny-Mills, Hebridean Whale and Dolphin Trust’s Science and Conservation Manager, highlights the importance of long-term monitoring of these species and the threats they face. She states, “In the face of the nature and climate emergencies, gaining new insights and understanding into what is happening in Scotland’s seas is vital, so we can better protect these remarkable animals and this world-class region of marine biodiversity.”
The Hebrides is a global hotspot for cetaceans, including whales, dolphins, and harbour porpoise, as well as the globally endangered basking shark. The Trust, based on the Isle of Mull, has been monitoring marine life since 2002 through its expeditions, with members of the public joining Silurian to survey the region’s seas.
The report reveals that the sighting rates of minke whales reached an all-time high of 1.57 per 100 km in 2023. The number of minke whales also saw a record increase, with a total of 167 sightings. In contrast, the rates for basking sharks decreased to 0.07 sightings per 100 km in 2022 and 2023, the lowest recorded by the Trust since its monitoring began. Only seven basking sharks were recorded in both summers.
The Trust explains that minke whales migrate to the western coast of Scotland each summer to feed in the exceptionally rich waters. While the increase in sightings is encouraging, the Trust emphasizes that sighting rates do fluctuate over time, and there are serious issues affecting this vulnerable species.
With human activities such as climate change, entanglement, pollution, underwater noise, and habitat degradation posing a threat to marine life, the Trust emphasizes the need for ongoing, long-term research to improve understanding of the impacts and how best to protect and restore biodiversity.
Marine Mobile Species Monitoring Advisor at NatureScot, Rona Sinclair, emphasizes the value of the Trust’s research in tracking the long-term health of whales and basking sharks in the Hebrides. She also stresses the importance of collaboration with organizations like the Hebridean Whale and Dolphin Trust in assessing the health of these species and understanding the reasons behind changes.
Ms. Sinclair expresses concern over the decrease in basking shark sightings and notes that there could be various reasons for this decline, including the availability of their food, zooplankton. She also highlights the need for continued collaboration with researchers to monitor the world’s second-largest fish and respond appropriately.
The new report, titled ‘Hebridean Cetacean Research Programme 2021-24’, documents data gathered during the Trust’s research expeditions from April 2021 to March 2024. The expeditions covered a total of 22,645 km and recorded 10 species of mammals in over 3,000 sightings. The Trust’s research relies on paying volunteers, who receive training and work as citizen scientists alongside marine experts. Those interested in joining Silurian’s 2025 research expeditions can visit hwdt.org/silurian for more information or contact info@hwdt.org or 01688 302620.
The new report, funded and published by NatureScot, is available on www.nature.scot.
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