Surge tide scheme protects 100,000 fish at Potter Heigham boatyard

Louise Taylor, second from right, with colleagues in the Environment Agency fisheries and biodiversi

Louise Taylor, second from right, with colleagues in the Environment Agency fisheries and biodiversity team. Picture: Environment Agency - Credit: Archant

An Environment Agency (EA) scheme has saved 100,000 fish from an influx of saltwater at a Potter Heigham boatyard.

The project at Herbert Woods saw a barrier installed across the boatyard entrance to be raised during surge tides, which push saltwater into tidal rivers.

It protects freshwater fish against the influx of saltwater, which can trap them in boatyards and dykes and can kill them.

A blog post written by Louise Taylor, of the EA's fisheries and biodiversity team, says: 'While we definitely feel the four seasons in Norfolk, we also experience another - the saline season.

'During this, generally, cold, wet and windy season - September through to March - surge tides push saltwater into the tidal rivers. However, add a strong northwest wind and we have a problem.


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'This sudden influx of saltwater can trap fish in the boatyards and dykes where they rest in over winter. This surprise is not good if you are a freshwater fish, and in the past, large numbers of fish have died.'

Once installed, she said knowing when to raise the barrier was a 'big team effort', which began with flood forecasting experts assessing when a surge tide was on its way.

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'However, this does not tell us how quickly the surge tide moves up the river,' the post says. 'This is where my team comes in. To find this out, we use some water quality monitors called sondes that record the level of salt in the river.'

The sondes enable the team to track the salt as it moves up the river - giving them enough time to raise the barrier.

The time last Friday, when the barrier was raised - saving an estimated 100,000 fish.

The blog says: 'We are so lucky to have a passionate community of anglers that also want to get involved.

'As a result, we have a network of volunteers that collect additional salt level data across other rivers. This increases our coverage during an incident and helps identify other areas that could be protected in the future. This really helps our understanding of these surge events and their impacts.'

• If you spot any fish in distress, call the incident hotline on 0800 80 70 60.

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