The above picture is a burn blockage event on the Allochrear burn near Blanefield.
The Loch Lomond Fisheries Trust has been actively dealing with blockage events, where a buildup of materials can build up at a particular spot in a river and/or burn and prevent ish and other aquatic organisms from migrating or passing through. These blockages can be caused by man made objects, or often by a fallen tree that then traps other woody debris and causes a large build up (see Figure 1 for example).
It is important for these blockages to be cleared safely and effectively, in order to create a channel for migratory fish such as salmon and trout to be able to pass through and access new habitat in which to spawn.
Whilst certain pieces of woody debris must be removed in order to allow a channel through the water, other pieces of woody debris have a positive effect on aquatic ecosystems, providing valuable habitat and cover from predators. Therefore, it is important to assess which objects causing the blockage should be removed and which pieces should stay in the water.
As illustrated, clearing a blockage can open up a great deal of important and valuable habitat, for spawning and other uses.