Between June and September 2021, GefaÖ carried out three surveys of the Middle Rhine in the area of Lorcher Werth and Bacharacher Werth (Rhine km 528.0 to 547.5) on behalf of the Waterways and Shipping Authority Rhine (Wasserstraßen- und Schifffahrtsamt Rhein) / Baader Konzept to survey the local fish population. The surveys were carried out by electrofishing, mainly from a boat, partly also wading – in the form of two line fisheries and one point fishery, each along the river bank regions or the groynes of the Rhine current.
Prior to the start of the fish population surveys, the water body structures were mapped during reconnaissance visits by boat in April 2021 and shortly before the start of the respective fishing campaigns. The hydromorphological conditions were recorded with regard to potential habitat structures for the fish species to be expected, especially with regard to the indicator and target fish species.
A total of 27 fish species and one species of cyclostomes (brook lamprey) were detected in the study reach during the three surveys. Among these 28 species, six were neozoa (stone moroko, prussian carp, kessler's goby, marbled goby, round goby and sunfish).