Celtic Sea acoustic sensors map marine mammals before floating wind development begins

No wind turbines are floating nearby these machines.

This is the whole idea.

Twenty-one acoustic devices have been installed in the Celtic Sea, located at the bottom of the sea and recording ocean sounds, while the operation of large-scale floating wind farms has not started yet.

The moored units are fitted with broadband acoustic sensors that can record sound waves from multiple frequencies and not just listen to one single frequency.

They can be compared to dictaphones.

They are placed 12 miles away from each other.

Their aim is to create regional images of marine mammal locations.

Twenty-one stations make one listening network

The 21 stations were launched by ORE Catapult in October 2025 as part of the three-year project SubSea Soundscape.

The moored units are fitted with broadband acoustic sensors that can record sound waves from multiple frequencies and not just listen to one single frequency.

Additionally, there is a pop-up retrieval system, as well as the capability of detecting animal tags or research devices.

Researchers go back to the sites to conduct further environmental monitoring, including eDNA sampling and measurement of the water column.

This means that sound waves form just one part of the data collected.

The water itself forms another layer of the data set.

 

A call can reveal an animal the surface misses

Satellites have eyes for the sea above.

Satellites do not have ears for below.

Marine mammals emit sound underwater as part of behavior like communication and navigation, and passive acoustic monitoring provides information about animals without using a vessel to view them on the surface.

The Celtic Sea stations just sit there and listen.

Matthew Witt of the University of Exeter called them seabed dictaphones as they continuously create a picture of the environment that is not possible with conventional visual technology.

Celtic Sea Power has created SealSpy, an acoustic classifier specifically made to identify seal vocalizations under the water.

The machine does not require the animal to come up to the surface.

It requires the animal to make a sound.

The map is the real instrument

Just 21 recorders cannot solve the issue of floating wind noise.

This research will allow combining their acoustic data with already known information and constructing a soundscape map for the whole area.

The idea of creating such a map is to identify patterns of underwater noise and marine mammal activity in the Celtic Sea as a whole rather than to restrict the ecosystem to observations of a single turbine site.

The scale is important.

Marine mammals can move through much larger distances than the project survey area.

So a limited investigation may capture only what an animal was doing in one part of the sea but not where it started and what happened next.

SubSea Soundscape seeks to hear the sea from the scale of marine mammals’ life.

Floating wind needs the before picture

It is in the timing that makes the recordings worthwhile.

Any future floating offshore wind development will lead to the emergence of new structures in the areas of the Celtic Sea.

For the researchers to be able to determine how the distribution of the animals changes, they have to be aware of how it was before the development process.

SubSea Soundscape is a £2.7 million study that is funded under the Offshore Wind Evidence and Change initiative from The Crown Estate, which will help to create such a baseline.

The evidence will be used during the evaluation of turbine placement and effects.

The results will eventually be made public through the Marine Data Exchange.

The recorders have not delivered the answer yet

The project is ongoing.

ORE Catapult also makes it clear that the current data extract is incomplete and shouldn’t be used for any conclusions about trends, findings, and even outcomes of the project.

SubSea Soundscape will come to its end in December 2027, according to the University of Exeter.

At this point, the team hopes to have created an open baseline acoustic dataset, a regional soundscape model, and a regulatory framework that can be useful in the decision-making process related to offshore wind development in England and Wales.

This is the reason for starting the listening in the first place.

Once the turbines are in place, every new sound is being heard in a sea that has been full of activity from the very beginning.

It is these 21 dictaphones that are going to record all the sounds of the sea.