Positive Bestandsentwicklung der Koppe (Cottus gobio Linnaeus, 1758) zwischen 2000 und 2020 in den Gewässern Südtirols

Increasing populations of the European bullhead (Cottus gobio Linnaeus, 1758) between 2000 and 2020 in the waters of South Tyrol

The European bullhead (Cottus gobio) is a fish species listed in the Annex II of the Habitat Directive of the European Union, but its status and population trends have not been estimated so far. In general, estimations for a larger region are rarely possible, mainly due to lack of data. Here, we use a data set from the Office for Wildlife Management consisting of > 1300 surveys from 659 different lakes or river sections across South Tyrol, of which 98 sites have been fished multiple times.

Across the region that covers 7400 km² of the Central European Alps, most monitored populations (78 %) increased in density with an average increase of 7 ±3 % per year. The few populations with negative population trends were not geographically clustered. We conclude that bullhead populations have predominantly increased across the province, most probably due to improved water quality and habitat availability over the last few decades and despite the stocking measures of brown trout throughout the study area.