Conservation Fish Survey in the River Blackwater

The Environment Agency (EA) conduct regular monitoring of fish stocks in the River Blackwater,  with one recent survey of Hawley Meadows shown in their video clip below.

They use a technique called ‘depletion surveys’ as part of the National Monitoring Programme. This monitoring is in accordance the Water Framework Directive (WFD) sampling programme. Which is a piece of European Union legislation designed to preserve, restore and improve the water environment. It establishes a framework for managing the water environment in a holistic manner taking into account environmental, social and economic factors.

A fixed transect of river is netted at either end then the fish stunned, retrieved, measured, then released unharmed back into the river.  This technique is very effective at establishing the health and size of individual fish, the biodiversity or range of species, as well as the fish density and total biomass for the transect.

This monitoring is useful to measure the success of conservation work we have carried out to increase the range of habitats in the river. Working with the EA, Wild Trout Trust and our volunteers, we’ve secured large woody debris and hawthorn brash in the river, and created riffles and gravel beds. By altering the channel dynamics, quiet spots are developed for sheltering fish, whilst faster flow scours off overlying silt exposing gravel beds for spawning. This EA monitoring demonstrated that following our river improvements, the density of fish increased 4-fold in 2012 to 0.9 fish/m2.

Ranger Stuart

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About blackwatervalleycountryside

The Blackwater Valley is located on the borders of Hampshire, Surrey and Berkshire and runs for approximately 30km from the source near Aldershot, northwards to Swallowfield. At its confluence it joins the rivers Whitewater and Loddon. The Loddon eventually flows into the River Thames near Reading. Work in the Blackwater Valley is co-ordinated by the Blackwater Valley Countryside Partnership on behalf of the local authorities that border the Valley. Despite being surrounded by urban development the Valley provides an important green corridor for local residents As well as the Blackwater Valley Site of Special Scientific Interest (SSSI) and a small part of the Basingstoke Canal SSSI, three nature reserves within the Valley catchment and many other areas have been recognised for their ecological importance. The local planning authorities covering the Valley have designated 31 other areas as ‘Wildlife Sites’.
This entry was posted in Conservation, Hawley Meadow, River, Volunteers, Wildlife and tagged , , . Bookmark the permalink.

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