For each flow, the Project team determined the river connectivity, or – by means of a visual census – the identification of those obstacles (natural or artificial barriers) that limit the movement and the fish lit. The sections of the waterways downstream of the 30 sampling sites of the chemical-physical analyzes and of the substrate were inspected.
• The significant horizontal artificial barriers in the Biferno basin in the project area are: 1) Quirino Torrent: runs intubated upstream of the confluence with the Biferno River; 2) Quirino stream: insurmountable barrier, Guardaregia dam; 3) Torrente Callora: a series of bridles, two of which are insurmountable upstream of the confluence with the Rio Santa Maria. The downstream section goes completely dry during the summer; 4) small bridle in Bojano downstream of the Sources of Pietre Cadute; 5) a series of three bridles with an existing fish passage (to evaluate its functionality) in the downstream section of the CIPM Reserve; 6) Rio Santa Maria: surmountable bridle with cementing of the riverbed on Rio S. Maria between the confluence with the Biferno River and the confluence with the Callora Torrent.
• The horizontal artificial barriers in the Volturno basin in the project area are: 7) Volturno River: surmountable bridle at Colli a Volturno; 8) River Volturno: insurmountable high bridle at Colli a Volturno; socket for the canal of the irrigation consortium; 9) River Volturno: two bridles that can be surmounted near “Ponte Rosso”; 10) Volturno River: anti-flood sink, surmountable but cemented; 11) Rio Caprionero: bridle and cementation on the Caprionero (the combination makes it insurmountable or unfavorable to the migration of breeding animals).
The obstacles that have priority for removal are obviously those that prevent trout from reaching breeding sites. But where do they go to reproduce more frequently? We will find out thanks to the genetic analyzes and tags that we inserted in the specimens sampled last season.