Fish Guidance Systems


Plans to develop a network of six tidal lagoons to generate power in the United Kingdom have moved a step forward in March 2015 following a £1bn funding boost for a tidal lagoon to generate power in Swansea Bay, south west Wales.

The Government has already thrown its weight behind the plans, naming the Swansea Bay Tidal Lagoon in the National Infrastructure Plan last year.

If the plans are agreed, a six-mile-long U-shaped seawall would run from the docks to near Swansea University's new Fabian Way campus. It would take two years to build and create 1,850 construction jobs.

When completed, the network would consist of six lagoons located near Cardiff, Swansea, Newport, West Cumbria, Colwyn Bay and Bridgwater Bay. Together they could provide 8% of the UK's electricity over 120 years, helping the UK to meet its carbon reduction targets by saving more than 236,000 tonnes of carbon dioxide each year.

Each lagoon would generate power for about 14 hours a day, as water passes through turbines embedded in the sea walls. Gates in the lagoon walls would be closed to keep water out as the tide rises, then opened soon after high tide, allowing water to rush in and turn the turbines. Gates would then be shut, keeping the water in until soon after low tide, when they would be opened to let the water out and turn the turbines again.

However, whilst energy from tidal lagoons brings enormous environmental benefits in the form of significant carbon reduction in comparison to burning fossil fuels, there are concerns about the potential impact to the marine habitat. The environmental impact of each project must be carefully assessed and anglers in particular are concerned that tidal lagoons could disrupt migrating fish stocks.

Dr David Lambert, UK General Manager of FGS commented 'the United Kingdom has the best tidal resource in Europe and the second best worldwide, and although the development of tidal lagoons provides a sustainable way to make the most of this natural advantage, there is a need to reduce any adverse environmental impacts. Fish can move through sluice gates safely, but when the gates are closed fish will potentially be drawn towards the turbines. If the approach velocity exceeds the swimming speed of the fish they will be entrained into the flow. This can lead to the fish being killed or injured as a result of either direct blade strikes or the significant pressure changes the fish experience passing through the turbines.'

Alternative passage technologies such as fish ladders, fish lifts and fish escalators have so far proved unsuccessful in solving this problem for tidal barrages and so the potential solution is linked to deterring the fish from entering the turbines.

Fish Guidance Systems has a variety of acoustic fish deflection systems that can deter fish from intakes. Contact David Lambert for further details.