Fish protected in £16m flood defence scheme

Jan 23 2010 by Tony Henderson, The Journal

Creature comforts have not been overlooked in a multi-million-pound flood scheme, Environment Editor Tony Henderson reports.

NO STONE was left unturned in weighing up the potential impact of a £16m flood protection scheme on river creatures.

The Environment Agency’s proposed project for Morpeth includes an upstream storage area on the Mitford estate which would take water from the River Wansbeck in flood conditions.

But a survey five years ago showed that the river’s population of native white-clawed crayfish is of national importance.

The native crayfish is in decline because of the advance of the imported American signal crayfish.

Another pressure comes from fragmentation of its habitat, and it was necessary to find out if structures associated with the flood protection scheme would divide the Wansbeck population in two.

Durham University was called in to investigate if culverts in the river would prove an obstacle to crayfish movement.

Ironically, a temporary culvert placed in the river as part of the experiment was washed away by flood water.

But work has continued, also using an existing culvert in the Cotting Burn at Morpeth.

Crayfish have been fitted with electronic tags and microchips so that their movements can be tracked to see if they move freely through culverts.

This has proved to be the case, although at one stage researchers thought they were tracking the fastest crayfish in the west.

It turned out to be a rat which had eaten two crayfish – and their electronic tags.

The crayfish will be helped further by the creation of “river bed” features inside culverts, such as crevices where they can rest.

They were also given priority during an operation at East Mill on the River Wansbeck where a site has been the location for the natural deposition of gravel since at least 1866. As this was a potential obstruction in flood conditions, it was decided to remove the top of the mid-channel gravel bar.

Crayfish were collected from the work area and released some distance away.