Nuclear Fishing

It’s looking pretty certain that nuclear power is going to play an important role in meeting the UK’s energy demands in a low(ish) carbon future. Various other schemes, perhaps most notably the planned Severn barrage, are starting to look too expensive and, ironically, environmentally unacceptable. I say ironically, because nuclear power has long been unpalatable to the environmental movement. But, faced with the choice between the certain destruction of large areas of ecologically sensitive wetlands, and the remote possibility of a nuclear catastrophe, many environmentalists are starting to think that uranium’s not such a bad option.

Now, I don’t want to enter the debate about how safe nuclear power really is, nor about the actual carbon emissions (factoring in building, running and decomissioning) of ‘carbon free’ nuclear power. Frankly, if I want to be able to power this laptop and see the occasional landscape free of turbines, like Lovelock I can’t see much alternative. But, there is an interesting environmental impact of nuclear power stations that is not widely appreciated: their effects on fish stocks.

Nuclear power stations in the UK are all situated on the coast, for the simple reason that they require a constant supply of very large quantities of water to cool the reactors. This water is not contaminated (except thermally – bays and estuaries near the power stations tend to be rather warm, altering growth and phenology of some marine species) – but, there is still an impact. As well as sucking in sea water, these installations also, of course, suck in anything living in it.

Big things – fish, for example – do not mix well with power stations, and so are removed using a large screen. Everything over a minimum size will be retained. Survival is not high.

Of course, any callous ecologists reading this (is there any other kind?!) will immediately think, ‘that sounds like a fabulous sampling strategy’. Well, you’re too late – I only know all this because of a series of really interesting papers involving Peter Henderson, a fish ecologist from the University of Oxford and PISCES conservation who has been collecting data monthly from one power station (Hinkley Point, on the Severn esturary) for almost 30 years.

In a recent paper, Henderson and Anne Magurran, one of his regular collaborators in this work, confirm that

The sampling method will… catch adults and juveniles older than six months for all known British marine fishes

What struck me, reading this particular paper, is that the numbers presented allow some very rough guesstimates of the fish catch of the UK’s nuclear power stations. For instance, they describe a (mightily impressive) sample over 24 hours across 4 intake screens in Hinkley. I don’t know how many screens there are in total, but even just taking these 4, the intake trapped ‘approximately 20000 individuals from 49 fish species’. Simply multiplying by 365 gives an annual take on the order of 7.3 million individual fish. Times eight power stations in the UK, and with catches of decapod crustaceans (crabs, shrimp, and so on) around four times those of fish – the numbers quickly become colossal.

In the grand scheme of things, the fish killed by nuclear power stations pale into insignificance against the catch of the monstrous global fishing fleet, and the unprecedented threat of global climate change. But, power stations can be designed to eliminate this, using recirculation of water or even dry cooling. I wonder, if more people were aware of the terrific waste of prime marine protein that currently occurs, might we be prepared to pay the extra for such a system?