FISH in the River Calder are in for a shock this summer.

An electric current will be fed into the river - which flows through Kirklees and Calderdale - to stun them before they are hauled from the water in a net.

But it's being done for a good cause - so they can be counted and measured in a survey. Environment Agency staff will be on the river over the summer to do their count.

The electro-fishing technique causes no harm or distress, say experts.

Survey leader Paul Curry said: "These annual surveys give us vital information, enabling us to assess the current status of fish stocks and identify any changes in populations that may have occurred over recent years.

"It is also invaluable for putting together future action plans for improving the local environment."

A small number of scales will be removed from each fish to give an indication of their age and growth rates.

Workers will be operating from boats as well as wading in shallow water.