The houting only lives in the Wadden Sea area, where it feeds, and spawns in the larger watercourses during the autumn. Today, natural populations only spawn in the watercourses of south-west Jutland , Denmark .
Only those watercourses which allow free passage can be used for spawning. Even small falls and dams can effectively block the passage of the houting to the spawning grounds, and it will not use fish ladders. The only form of fish passage which the houting can certainly clear are sweeps with large flows.
The houting spawns in the lower and central parts of the watercourses where the bed is at least 5-6 metres wide. The mature houting looks forreaches with a good current, a firm bed and evergreen aquatic plants.
In the Varde Å river, the dams for fish farming and that linked to the Karlsgårde power plant, have cut off the houting from spawning grounds in sections of the old Varde Å and the tributaries Alslev Å, Grindsted Å, Ansager Å and Holme Å.
In Sneum Å the houting are cut off from the spawning areas above the fish farm at Endrup Mill. The largest tributary Bramming/Holsted Å is completely blocked off by the weir at Bramming Fishery.
There are several dams in the Kongeå. At the first dam, a by-pass channel has been established, giving houting access around the fish farm at Jedsted Mill. The next obstacle is about 20 km further upstream, where the weir at Nielsby Fish Farm prevents them from ascending any further up the Kongeå.
In the Ribe Å they can only reach as far as the dams in the city of Ribe itself. However, there are good spawning conditions in the Hjortvad Å tributary, where the houting have unimpeded access to the entire watercourse. The fish spawn in an approximately 10-12 km long stretch from Kalvslund to Ribe.
The best passage conditions are found in the Brede Å.Here the houting have free access to the whole river system, as all obstacles and dams have been removed. However, the river suffers partly from ochre.
The Vidå offers reasonably good passage conditions to a large part of the system. However, the Arnå - in the northern branch of the Vidå system - is blocked off to houting by a large dam in the town of Tønder . In theGrønå branch free passage has been created, although there are still obstacles in the Sønderå branch at the Rens fish farm.