Fish protection measures at Hinkley Point C

Hinkley Point C’s acoustic fish deterrent uses different technology compared to the previously considered option of placing 275 powered loudspeakers out at sea.  The ultrasound deterrent operates with high and low-frequency sounds to target different types of hearing fish, including salmon and twaite shad. These systems do not harm the fish and can be tuned for specific species, therefore avoiding disturbance for larger marine mammals like dolphins or seals. This kind of high-frequency sound is already used in fishing fleets around the world to reduce bycatch.

Because the system uses ultrasound, it is smaller than a system using audio speakers with high voltage power cables. That means it can be self-powered using batteries, retrieved and maintained from the surface without the need for divers to operate in some of the most dangerous waters in the world with huge tidal flows and very poor visibility.

Based in Totnes, Devon, Fishtek marine design and manufacture products that reduce the environmental impact of commercial fishing and other marine operations. They combine engineering with fisheries science to create practical, industry‑ready solutions, and their products are used in more than 40 countries.

During the summer of 2025, hundreds of salmon and twaite shad were tagged with small electronic beacons in rivers around the Severn Estuary, including the Tywi, Usk and the Wye. 86 separate receivers were also deployed across the Estuary and around Hinkley Point C’s water intakes to detect the fish. At the same time, 36 acoustic fish deterrent units were setup around two of the intake heads, whilst the remaining two had no acoustic fish deterrents around them. By comparing the difference between the two, the team from Swansea University have been able to show that the system is highly effective at deterring fish from the areas around the intake heads.

Hinkley Point C will be the first power station on the Severn with protections for fish built into its design, including specially designed low velocity cooling water intake heads and a fish return system. With these two protections, the remaining impact on fish in the Severn Estuary would be small and has been assessed with the Environment Agency at 44 tonnes a year, less than the annual catch of one small fishing vessel. With an acoustic fish deterrent, it will be even smaller.

In 2024, ultrasound acoustic fish deterrent technology had not been considered for Hinkley Point C. Instead, the project looked at deploying existing loudspeaker technology. Detailed investigations showed that a speaker-based system would pose serious risks to divers having to maintain the system in the dangerous waters of the Bristol Channel over 80 years. To avoid these risks to life, Hinkley Point C considered meeting environmental regulations through the creation of 900 acres of new saltmarsh to compensate for the very small remaining impact on fish. The marsh would have provided feeding and breeding grounds for some species. These proposals would have impacted farms and communities along the Severn. 

The success of tests on the acoustic fish deterrent means that the saltmarsh should not be required. However, until environmental regulators approve the new system for use, the need for saltmarsh or improvement to weirs further up the Severn Estuary cannot be ruled out.

This innovative technology was not available when the power station gained planning consent in 2013. It has been pioneered and successfully deployed in the fishing industry to reduce by-catch and applying it to power stations had not been considered before.

The system would be tuned to maximise the effectiveness of fish deterrence whilst minimising impacts on larger marine mammals like seals and dolphins. This technology is being developed with the potential to provide flexibility when “tuning” a system to deter specific species of fish present within the Severn Estuary, whilst potentially avoiding impacts on larger mammals.