## 4 Discussion  
The fishery managers agreed on ten key conservation measures that led to successful brown trout conservation strategy on salmonid streams in central Europe. The measures mainly consisted of the assessment of brown trout populations, unified approach of all fishery managers together, restoration of salmonid streams, adjusted fish stocking strategy,angling regulations, and support of brown trout in aquaculture production. The measures will now be discussed. Firstly, the fishery managers agreed on the need to assess local brown trout populations. This included the analysis of their genetic origin as well. The goal was to find if the populations are 100% local and not inbred with the commercially stocked brown trout from hatcheries. However, the fishery managers confessed that they cannot reliably assess the populations because they lack the proper equipment and resources to do so. Instead, they sampled a small number of trout (20 randomly selected fish) caught on 500 m of each stream, and they extrapolated the results on the entire stream (hundreds of fish on 10-15 km long streams). The populations could therefore be partially inbred because, as other studies found, pristine brown trout populations are quite rare in central Europe [17; 18]. The second issue was that the fishery managers are not yet well organised. In the Czech Republic, all the fishery managers are united under the Czech Fishing Union, but the interviewed fishery managers said that this organisation is too wide and un-focused for their needs. They argued that it is difficult to connect with all the other fishery managers who also manage streams with brown trout populations. They said that the Czech Fishing Union is not supportive enough because it is focused on the financial profit of selling fishing permits rather than conservation of wild fish populations. The managers are working on the conservation measures in their free time and on their expenses. Since other countries often do not have a centralised body that unites all fishery managers, their organisation is going to be even more difficult in these countries [19]. The third issue was the poor ecological status of streams in central Europe. Fishery managers agreed that the streams often dry up during hot rainless summers due to channeling and straightening of the flow. They also claimed to have negative experience with owners of local hydropower plants who do not comply with the minimum water levels in the streams that are set by the legislative measures. The fishery managers claim that it is difficult to prove that the plant owners have broken the rules. During hot summers, if the water level in the stream falls below the minimum levels, the trout start dying due to low oxygen levels in the water. If this happens frequently, the fishery managers refuse to stock and protect resident brown trout because they are likely to perish in the summeranyway. Other studies confirmed their opinion that brown trout populations are vulnerable to droughs and lower water levels [20, 21]. The fourth issue was fish stocking. The managers claimed that stocking of any fish that is not of local origin is bad for the brown trout populations. Especially harmful are other salmonids that compete for food (rainbow trout, brook trout, and commercial brown trout) and predators (pike _Esox lucius_ and pikeperch _Sander lucioperca_). They are calling for a ban of fish stocking on the streams where naturally self-reproducing brown trout populations exist. It is because studies have shown that angling pressure negatively affects salmonids [5, 7]. The problem is that anglers buy permits, and they pay for the fishery management, meaning that without the anglers' money, fishery managers will have less money for their conservation actions. If the brown trout populations need to be bolstered (e.g., after unexpected floods, droughs, or natural disasters), only eggs of local and genetically similar trout should be used.