The distribution and richness of the Italian riverine fish provided by the BioFresh database

Freshwater fish are recognized to be endangered worldwide, but wide gaps in species distribution knowledge limit the implementation of effective conservation plans. The BioFresh project aims to produce the widest synthesis at the national level. The aim of this research is assessing the comprehensiveness and representativeness of information included in the Italian synthesis, composed of 10000 sampling sites and 50000 fish presence records. The assessment was produced at the secondary river basin (SRB) level in two distinct periods, past (1984-1999) and recent (2000-2014), comparing different statistical models of frequency counts of species detected within each SRB. The results highlighted a poor overall knowledge of the Italian fish distribution for both periods. In the all-species dataset, only 11.8 % and 11.1 % of the SRBs were found to have been sufficiently explored in the past and recent periods, respectively. In the native species dataset, these percentages increased to 16 % and 24.7 % respectively, which suggests the presence of background noise in the richness estimates produced by exotic species. Although the information available is far from exhaustive, the BioFresh project, in which data collected over a wide time span are georeferenced and freely available, represents the first synthesis for future research aimed at the management and conservation of the Italian fish fauna.