Clocking speeds of the fish

In the first study of its kind the Environment Agency has been clocking the speeds of the fish that inhabit our rivers and streams. The new research will help the Agency design "ladders" that can be built into weirs to allow coarse fish to swim over them.

To design and build the most effective ladders scientists needed to know how fast fish swim. A special pool built to allow marine experts to vary the temperature and speed of water flows was used to test how fast and for how long certain species can swim in different conditions.

Trout takes the honour as fastest fish in English and Welsh waters slicing through the water at 2.1 metres a second, around 4.7 miles per hour. Other freshwater, or coarse, fish such as roach, dace and chub are not far behind at 1.8 metres a second. Elvers, whose numbers have dramatically declined over recent years, bring up the rear only managing a sluggish 0.5 metres a second.

Structures such as sluices, culverts, weirs, fish passes and water intakes can all prevent or interfere with natural fish movements and migrations potentially damaging fish stocks. Its hoped the findings will help improve coarse fish populations throughout the country and is expected to attract international interest. "Basically, we are just giving nature a helping hand. Healthy fish populations mean improved bio-diversity which will create a richer, more diverse environment for us all to enjoy" says Andy Strevens for the Environment Agency. "The findings are a real boost for the Agency here in the South West after our pioneering work in this area at Hurn weir on the Moors River in Dorset where with help from engineers at Exeter University we redesigned the weir to allow dace upstream. With this new information our future work can be tailored precisely to the needs of all types of fish from the outset."