Extent of bullhead

Extent of the European bullhead (Cottus gobio) in watercourses within the Krkonoše SCI
A mapping of watercourses within the Krkonoše SCI took place in 2012-2013, intended to contribute to understanding the geographic extent of the European bullhead (Cottus gobio) in the study area. The work was done with support from the European Union financial instrument LIFE+, project LIFE CORCONTICA (LIFE11 NAT/CZ/490). Based on the research results, this stage of the LIFE CORCONTICA project (www.krnap.cz/life) will be followed by additional activities in the form of design and implementation of revitalisation measures, making transverse obstacles in the watercourses passable, and repatriation of the bullhead into suitable watercourses as necessary.
Watercourses of the third and higher orders according to Strahler within the Krkonoše SCI and other segments with a potential of European bullhead (Cottus gobio) presence were selected for the field mapping. The hydromorphology of the study watercourses was mapped first with a view to the potential presence of the European bullhead. The field mapping of the hydromorphology consisted in physical examination of the study segments, recording of predefined characteristics and major transverse obstacles representing potential barriers to the natural extent of the species. The outcome of the hydromorphology mapping with a view to determining the potential extent of the European bullhead is a linear layer in the shapefile (.shp) format processed in a GIS environment, permitting presentation of the extent of the European bullhead as a simple cartogram.
Based on available data on the extent of the European bullhead within and near the Krkonoše SCI and with a view to the results of the watercourse hydromorphology mapping focused on the potential extent of the study species, we designed survey profiles for establishing the area of extent of the European bullhead (Cottus gobio). The field mapping for the presence of the European bullhead also registered presence of other fish and lamprey species. The field mapping for the extent of the European bullhead and detection of the status of the fish association within the Krkonoše SCI was done using the conventional electrical fishing method according to a predefined methodology.
The hydromorphology mapping focused on potential presence of the European bullhead mapped a total of 302 transverse structures and hydromorphology of study watercourse sections approx. 280 km long. The mapping results and analysis of data obtained indicate that the Krkonoše SCI has approx. 132 km of sections of study watercourses with optimum or satisfactory (45 km optimum and 87 km acceptable) hydromorphology for the presence and development of viable European bullhead (Cottus gobio) populations. It can be concluded based on the results of the survey of the extent of the European bullhead (Cottus gobio) in watercourses within the Krkonoše SCI (survey made at 52 profiles; see graphic annex) that viable populations of the European bullhead are present in approx. 68 km of watercourse sections within the SCI.
The results of the analysis of data obtained indicate that the strongest populations of the European bullhead are present primarily in the arterial watercourses of sub-catchment areas. These include the Jizera river, with the upper boundary of the range of extent being downstream of Jablonec nad Jizerou a continuing downstream beyond the SCI boundary. Bullheads are also present in tributaries to the Jizera, namely the Roudnický, Vejpálický and Františkovský brooks. In this catchment area within the SCI, another centre of presence of the bullheads is in the Jizerka river, particularly the section upstream of Víchová nad Jizerou up to Vítkovice. In the Elbe catchment area, the centre of bullhead presence is in the arterial watercourse, the Elbe from the Elbe Reservoir to Vrchlabí, as well as the Malé Labe, particularly in the section between Lánov and Dolní Dvůr. Another strong European bullhead population in the Elbe catchment area is in the Luční brook. Presence of bullhead populations have also been confirmed in the Bolkovský brook, with isolated finds in the Husí brook upstream of its confluence with the Malé Labe and in Malé Labe itself upstream of Strážné. Strong populations of the European bullhead in the Úpa catchment area are found in the Úpa itself and its tributary the Malá Úpa. Bullheads have not been confirmed in any other of the Úpa’s tributaries in this catchment area within the Krkonoše SCI.