Distribution and abundance of european bullhead Cottus gobio in the watercourses of Pesaro-Urbino province (Marche, central Italy)

Cottus gobio is a widespread species in Europe and the Marche Region (Central Italy) represents the southern limit of its range of distribution in Italy. C. gobio is listed as Vulnerable in the Red List of Italian Vertebrates, but little is known about the status of Italian populations. Thus the main aims of the study were to (i) analyze the distribution of C. gobio in some watercourses of Pesaro-Urbino Province (Marche Region), (ii) increase the information on ecological preferences of this species and (iii) investigate the differences in habitat selection between C. gobio and Salmo trutta. Data on 35 sampling stations located in 22 watercourses of Marche Region were used for the analyses. In each sampling station the main environmental variables were measured. The relationship between fish fauna and environmental variables were investigated by the Analysis of Canonical Correspondence. C. gobio was found only in 15 sampling sites with few isolated populations. This situation arise concern, since the fragmentation of populations poses difficulties for migrations and thereby increase the possibility of local extinction. In 14 stations out of 15, C. gobio occurs together with S. trutta. Even if the two species share common habitat preferences, some differences in the microhabitat selection emerged. The information collected allowed to increase the basic knowledge on ecology of C. gobio and provide useful data for the management and conservation of the populations.