Aerial survey confirms rich biodiversity of marine waters

A two-year long aerial survey by a team of researchers at University College Cork has provided new details of a rich biodiversity in Ireland's marine waters.

The ObSERVE Phase II Aerial Project found an extraordinary range of seabirds and other animals off Ireland’s south and southwest coast, including rare species such as the blue whale, and deep-diving beaked whales, as well as more common species such as pilot whales and bottlenose dolphins.

It also confirmed that the seas around Ireland are important foraging ground for leatherback turtles and dozens of seabird species such as puffins, guillemots, petrels, gannets and shearwaters.

A large portion of Ireland’s maritime area of almost 490,000 square kilometres was included in the survey.

The results will help to inform the assessment of risk to protected species and provides data for assessment of the conservation status of species in Irish waters and contribute to sustainable management of its maritime area.

Irish coastal waters important for seabirds throughout the year

Three broad-scale aerial surveys were conducted for this report. They took place during summer 2021, summer 2022, and winter 2022.

Altogether this resulted in almost 39,400 sightings of seabirds including 24 seabird species such as northern gannets, black-legged kittiwakes, northern fulmars, and common guillemots.

There were also almost 2,200 sightings of 17 species of cetaceans, including common dolphins, bottlenose dolphins, harbour porpoise and minke whales, as well as rarer sightings of species such as killer whales and beaked whales.

Other species sighted included sunfish, basking sharks, and blue sharks.

The study confirmed that Irish coastal waters are particularly important for seabirds throughout the year.

Guillemots, puffins, razorbills petrels, gannets and Manx shearwaters were primarily recorded in summer, while fulmars and black-legged kittiwakes were seen in greater numbers in winter.

The entire area was estimated to support over 1.5 million seabirds in both summer and winter, with certain seabird 'hotspots’ in the Irish Sea and coastal waters off the southwest and west coasts.

At least three species of the deep-diving, and poorly-known beaked whales were recorded, with an estimated 2,000 individuals in summer and 3,700 in winter, primarily concentrated along the continental shelf break along the west coast of Ireland.

Sightings of rarer species such as false killer whale also occurred.

Common dolphins were the most abundant cetacean species, while bottlenose dolphins were the second most abundant.

The Celtic Sea and coastal areas of the west coast were highlighted as the most important for both dolphin species.

The number of harbour porpoise, the smallest cetacean in Irish waters, was particularly low in 2022, with just 7,500 individuals in summer and 6,600 individuals in winter.

Minke whale was the most frequently observed and most abundant of the baleen whales.

The larger fin and humpback whales were also recorded with Ireland’s continental shelf edge noted to be a particularly important area for fin whales, possibly as a migratory corridor or for foraging.

Density hotspots

The report says that identification of density hotspots for a range of sensitive and protected marine species is an important factor in considering the appropriate siting, monitoring and mitigation for development of offshore infrastructure including windfarms.

Ambitious targets for development of offshore wind energy generation by 2030 are largely based along the Irish and Celtic Seas that were studied in both phases of the aerial survey programme.

These are important regions for a range of seabirds, and some species of cetaceans such as harbour porpoise, bottlenose dolphin, common dolphin and minke whale.

Hotspots along the western coast in the vicinity of Galway Bay, around the southwest and southeast coasts and large areas in the Irish Sea are also designated for rapid development of offshore wind farms.

The seabird and cetacean distribution hotspots highlighted in this report will be important considerations for Environmental Impact Assessments required for these developments.

Also, interactions between seabirds and fisheries have been identified as a major contributor to global seabird declines through bycatch and over-exploitation of fish stocks.

Fisheries bycatch is a significant pressure on harbour porpoise and common dolphin, in particular.

Understanding hotspots of seabird and cetacean occurrence can help identify areas for targeted conservation efforts and mitigation where they will have the greatest impact on seabird populations.

Speaking on the publication of the ObSERVE II Aerial Project Reports, Minister of State with responsibility for Communications and Circular Economy, Ossian Smyth TD said: "This information will help inform the way forward for future regulation and sustainable management of Ireland’s maritime area in tandem with advancing the conservation of protected species, and the identification of important areas for their natural ecology and its conservation."

Minister of State with responsibility for Nature, Heritage and Electoral Reform Malcolm Noonan TD said: "The ecological data amassed by this project will further enable the development of evidence-based approaches for the conservation of Ireland’s biodiversity."