Humpback whales are arriving at the Irish coastline significantly earlier each year, a shift researchers have linked to rising ocean temperatures and changes in prey distribution. According to a study led by ATU Galway PhD student Miguel Blásquez, the first seasonal sighting of the species moved from 15 September in 1999 to 2 March in 2023.
Did You Know? The duration of the humpback whale season in Irish waters has seen a dramatic expansion, growing from a 47-day window in 1999 to a 241-day period by 2023.
Why are whale arrival patterns changing?
The research, published in the Marine Mammal Science journal, indicates that the first annual sightings of humpback whales have shifted approximately nine days earlier every year between 1999 and 2023. Dr. Simon Berrow of the Irish Whale and Dolphin Group (IWDG) attributes this change to warming sea surface temperatures, which impact the movement and availability of pelagic and foraged fish, such as sprat and sand eels. While the whales are primarily in Irish waters to feed, these environmental shifts are altering their traditional behavior and geographical presence.
What is the impact on Irish coastal waters?
The study suggests that Ireland and nearby UK waters serve as vital feeding grounds for a subset of the humpback population that mainly reproduce in breeding grounds off Cape Verde. Current data estimates there are 154 humpback whales in the region, a population count that is rising. Dr. Berrow notes that the whales show improved body condition while in Irish waters, making this period essential for building the reserves they need to return to their breeding grounds. Recent observations also show a geographic shift, with whales appearing more frequently in Donegal Bay compared to the Cork coastline where the project first began.
Expert Insight: The rapid shift in arrival dates highlights a broader trend in marine ecology. When migratory predators like humpback whales adjust their arrival times, it suggests a disruption in the marine food web. Protecting the specific forage fish species these whales depend on is now a conservation priority.
What happens next for whale conservation?
Researchers suggest that implementing area-based protection measures may help mitigate the impact of human activities on these whales. As the species continues to support marine tourism, particularly in areas like Donegal Bay, experts emphasize the need for a balance between conservation and public access. Future management may focus on limiting disturbances to feeding whales and ensuring that the prey species—sprat and sand eels—remain abundant enough to sustain both the whales and other marine predators.
Frequently Asked Questions
How many humpback whales are currently in Irish waters?
Research has estimated that there are 154 humpback whales in Irish waters, a number that is increasing.
How was the data for this study collected?
The data was gathered through the IWDG’s “Whale Track Ireland” citizen science project, which recorded 1,127 photo-identified sightings from 226 different contributors between 1999 and 2023.
Where do the humpback whales seen in Ireland breed?
According to IWDG research, most of the humpback whales found in Irish waters breed off the coast of Cape Verde in west Africa, while some breed in the Caribbean.
How might the continued expansion of the whale-watching season change our approach to protecting these coastal habitats?
