The importance of marine wildlife to the ecosystem around Sizewell C cannot be overstated.

Everyone involved in coastal infrastructure projects in the UK has a responsibility to protect and promote such wildlife, using the best options available.

For many species that would be affected by the Sizewell C station, acoustic fish deterrents (AFDs) have proven to be the most effective means to protect against the risk of damage from cooling water intakes.

Among them are sprat and Atlantic herring, the latter a species of commercial and conservation importance.

Sprat inundations have previously put at risk operations at the existing Sizewell plants, while huge sprat shoals have been responsible for plant damage and millions of pounds worth of electricity generation at other East Coast sites such as Dungeness Power Station in Kent.

Minimising risk to fragile fish

Such incidents illustrate the risks of allowing fish to pass through cooling water intakes, not only to the safety of the fish themselves, but also to the station’s ability to maintain operation when needed.

But sprat and herring are classed as hearing specialists and AFDs are proven to prevent them from entering offshore intakes. Trials of an acoustic system installed at Belgium’s Doel nuclear power station showed 95% of herring were deflected, along with 88% of sprat.

Combined, these two species have made up nearly two-thirds of the annual kill by power stations at the Sizewell site, according to reports by the Centre for Environment, Fisheries and Aquaculture Science (Cefas).

EDF Energy have argued a fish recovery and return (FRR) system provides sufficient protection, when combined with a low velocity side entry intake. The latter is designed to prevent fish from being sucked in by reducing water speed, but Environment Agency guidance for new nuclear build sites concludes that once-through cooling can only be considered the Best Available Technology where an AFD system is also included.

Sprat and herring are fragile pelagic fish, whose scales easily shed. They very rarely survive passage through an FRR system, making an approach that fails to exclude them inherently flawed and falling short of the high standard of fish protection that is readily achievable

Learn about changes in the fish population at Sizewell C.

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