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Instream works
Instream works
Instream Works
In canalised stretches of river there is no variety in flow types and they are often bereft of spawning gravel locations for salmon and trout. Part of a project funded by Hanson Environment Fund was the creation of an artificial spawning bed in a straightened section of channel at the quarry. Adult trout have been seen in this section of channel however there is a lack of gravels for them to spawn in. Placing some large boulders into the stream channel will change the morphology of the channel – the hydraulic effect of the boulders causes the accumulation of gravels downstream. The boulders will also create habitat for a range of river invertebrates and can also provide hiding places for salmon and trout. In a channelised Irish stream trout numbers were recorded to increase by six times after boulders had been placed in the channel. Another way of creating a variety of instream flows and for generating cover for salmon and trout is by transplanting Ranunculus (Water Crowfoot) from areas of high densities to areas where it has been lost. A small section of the plant is dug up (including roots) and taken in water to the transplant site in early June. The fronds (leaves) are cut off so that once the roots are buried they have a chance to establish themselves before any floods can wash the plant out. Water crowfoot also provides a home for many species of instream invertebrates which in turn provide a good food source for many species including fish. |
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