A new study for Ireland’s marine regulator says that repeated geophysical and geotechnical surveys, which are also clustered and overlap with sensitive habitats, could negatively impact marine life.
As Afloat has reported, the Maritime Area Regulatory Authority (MARA) published a study this month examining the impacts of geophysical and geotechnical surveys on fish and shellfish in Irish waters. The afloat article cound be found here.
The study, entitled “Review of Impacts of Geophysical and Geotechnical Surveys on Marine Fish and Shellfish in Irish Waters”, highlights knowledge gaps regarding the impacts of underwater noise on marine life. It also says there is a “clear lack of empirical studies on the impacts of geotechnical surveys on fish, shellfish and crustaceans, meaning impact assessments often rely on extrapolation from other seabed-disturbing activities”.
“Short-term sub-lethal responses in fish, such as stress or temporary displacement, are particularly poorly quantified and require further investigation,” the report prepared by Aquafact (part of the APEM group) on behalf of MARA says.
While impulsive noise from seismic surveys and air guns is most consistently linked to short-term behavioural effects such as startle, avoidance, displacement and reduced foraging, more severe effects are mainly reported for eggs, larvae and shellfish, it says.
The report says that continuous noise is “more consistently linked to sublethal effects such as physiological stress, higher metabolic cost, altered behaviour and, in some cases, reduced reproductive success”.
“Habitat loss or removal from geotechnical surveys is expected to be highly localised, but effects may be more important and longer lasting in complex, low-resilience habitats such as reefs, coarse gravels and mixed substrates,” it says. “Suspended sediments and smothering are likely to pose the greatest risk to eggs, larvae, filter feeders and shellfish habitats, especially in low-energy environments,” the report says.
It says that cumulative impacts on marine life are “most relevant where surveys are repeated, clustered or overlap sensitive habitats or life stages, as repeat disturbances can compile and limit recovery”.
The report makes a number of recommendations, including introducing temporal restrictions on surveying to avoid spawning periods of key commercial species, such as Atlantic herring and Atlantic cod, or transition periods of diadromous fish (250 species, including salmon, trout, lamprey, and eel) between freshwater and saltwater.
Other recommendations relate to limiting noise and the risk of smothering habitats with sediment, and advise minimising survey repetition by maximising data sharing both internally and externally, as well as data re-use.
It says survey works should be “staggered to reduce cumulative disturbance to sensitive ecological receptors”, and says that implementation will “be best achieved through liaison with relevant public authorities and stakeholders”.
MARA says the report comes at a time of increasing offshore marine activity within MARA’s regulatory remit, including offshore renewable energy development, subsea infrastructure projects, and marine site investigations.
MARA chief executive Laura Brien said the report will “support informed decision-making across the marine sector”.
“As activity in Irish offshore waters continues to grow, it is essential that decision-making continues to be underpinned by robust scientific understanding and effective environmental stewardship,” she said. “The publication of the report reflects MARA’s ongoing commitment to regulate effectively and impartially, while supporting sustainable marine development,” she said.
MARA Study Raised Concerns About Impact of Surveys At Sea On Marine Life
About The Author
Lorna Siggins
Lorna Siggins is a print and radio reporter, and a former Irish Times western correspondent. She is the author of Search and Rescue: True stories of Irish Air-Sea Rescues and the Loss of R116 (2022); Everest Callling (1994) on the first Irish Everest expedition; Mayday! Mayday! (2004); and Once Upon a Time in the West: the Corrib gas controversy (2010). She is also co-producer with Sarah Blake of the Doc on One "Miracle in Galway Bay" which recently won a Celtic Media Award
We've got a favour to ask
More people are reading Afloat.ie than ever thanks to the power of the internet but we're in stormy seas because advertising revenues across the media are falling fast. Unlike many news sites, we haven't put up a paywall because we want to keep our marine journalism open.
Afloat.ie is Ireland's only full-time marine journalism team and it takes time, money and hard work to produce our content.
So you can see why we need to ask for your help.
If everyone chipped in, we can enhance our coverage and our future would be more secure. You can help us through a small donation. Thank you.

















































