Complete and fine-tune

Once the substrate has been sorted and larger stones and boulders have been removed, it can easily happen that the remaining gravel ends up too deep. This can be adjusted by raking the gravel toward the excavator and up to the edge of the spawning ground.
To control the water’s speed over the spawning ground, so-called anchoring boulders can be placed. Position these slightly larger boulders at the edge of the gravel area. By doing this, a “pen” is formed that helps to retain the gravel. Be sure to add coarse material below the crest of the spawning ground to ensure it is anchored even during high-energy flows.
To minimize the risk of the spawning gravel being washed away during high flows, the spawning area should have a sloping bottom profile that goes from deeper to shallower in the downstream direction. This is best adjusted by carefully guiding the gravel with a closed bucket without compacting it.
Larger boulders located high just upstream of the spawning area can create eddies that may displace the spawning gravel. To avoid this, make sure to move or lower larger boulders that are within 5-6 meters upstream of the spawning area.
In small to medium-sized watercourses, it is beneficial to fine-tune spawning grounds using spawning ground tools (stone hooks, bottom rakes, spawning ground forks, and sorting forks). Often, the excavator bucket is too bulky to fine-tune certain parts of the spawning ground.