Environment

Female sperm whales becoming more frequent off the coast of Ireland

Study examined available historical and contemporary data from whaling, stranding, and sighting records from 1910 to 2023

A large sperm whale washed up near Glencolumbcille in west Donegal. Photograph: NW Newspix
A large sperm whale washed up near Glencolumbcille in west Donegal. Photograph: NW Newspix
Anne Lucey
Sun Sept 22 2024 - 20:59

The presence of female sperm whales has become more frequent off the coast of Ireland, which could be linked to climate change, according to a new study.

The study on female, juvenile and calf sperm whale records from Ireland examines the apparent increasing frequency of female sperm whale strandings here.

The research found the current trend of female strandings in Ireland indicates the population structure in Irish waters may be altering from a primarily male only structure to include female groups also.

Seán O’Callaghan of the Marine and Freshwater Research Centre at Atlantic Technological University in Galway said “it remains to be seen” how offshore Irish waters alter as the effects of climate change become clearer in the years ahead.

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However, he said “the apparent increasing presence of female sperm whales is a signal of widespread habitat change for the species and other top predator communities”.

The study established the presence of female, juvenile and calf sperm whales off the coast of Ireland, at higher latitudes than within the range of the nursery grounds in the northeast Atlantic.

It relied on available historical and contemporary data from whaling, stranding and sighting records from 1910 to 2023.

“It appears that the population structure for sperm whales off Ireland began to change over the past decade from a primarily male-based population to now include females, as indicated by these stranding and sighting records,” the study noted.

[ Shining new light on sperm whales and the importance of Irish waters to them ]

It also pointed out that marine heatwaves have “increasingly become a concerning issue for the world’s oceans”, given that they permeate into deep water habitats and may affect depths down to 200m, while the duration of their effects also increases with depth.

Sea surface temperatures increased during a warm period from the mid-1990s to mid-2000s, peaking in 2007 when Irish waters were on average 0.8 degrees warmer than from 1960 to 1990.