Sizewell C and fish

By Marjorie Barnes | Published on 5 May 2021 | 2 min read

Direct-cooled power stations need large volumes of cooling water as part of the electricity generating process. As part of the impact assessment process, fisheries scientists predict the percentage of adult fish stocks taken each year by a power station, just as they would for commercial fishing. We will use a fish return system, just as we do at Sizewell B, to avoid the impact on fish as much as possible. We will also use a state-of-the art cooling water intake head, specifically engineered to minimise the number of fish captured in the first place.

In the wild, fish die in very large numbers from a variety of reasons, for example, they are eaten by predators, or suffer from disease. This natural mortality is typically 10 to 20% of the adult population per year for longer-lived species but 60% or more for shorter-lived shoaling species. Consequently, fish have evolved to produce incredibly large numbers of offspring each season to compensate for the large number that will not survive.  Fisheries scientists know that fishing can sustainably take at least 10 to 20% of the adult population every year without affecting the species’ ability to reproduce and maintain their population levels. For many species even higher levels of fishing are sustainable.

Our assessments show that the largest numbers of fish likely to be captured by Sizewell C are mainly sprat and herring. The predicted intake of these species is 0.01% of the stock in the area. Fisheries scientists describe the impact of new nuclear power stations on the wider marine ecosystem as ‘insignificant’ and state that there is no scientific evidence that the rates of impingement at Sizewell C will have a significant effect on population sizes and abundance trends of marine fishes.

Response to media coverage regarding Cefas’ Sizewell C advisory work – Cefas (Centre for Environment, Fisheries and Aquaculture Science)

Posted by Marjorie Barnes

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