Background The biggest threat to Bulgaria's rivers and their dependent species is fragmentation caused by the construction of artificial barriers, such as hydropower plants, bridges and erosion control features. Bulgaria has no national requirements for river infrastructure works to take into account the protection of river habitats by allowing for the migration of aquatic organisms upstream and downstream. Most of the country's river barriers were built from the 1960s-80s, an era of significant unsustainable industrial development and pollution, leading to the complete extinction of fish in many of the watersheds. Migration barriers and severe industrial pollution have made natural restocking a slow, random and sometimes impossible process. As a result, the populations of many species are severely reduced. Objectives The main project goal is the improvement of conservation status of six small rheophilic fish species and a mollusc species listed in Annex II of the EU Habitats Directive in selected river sections in Natura 2000 sites in the Bulgarian Danube river basin. Specific objectives include: Improving longitudinal connectivity, reducing river fragmentation and improving habitats in selected river stretches to support the migration of target species connectivity of populations; Direct restocking to strengthen populations of the target species; Building capacity and involving institutions and other stakeholders to consider the issues of longitudinal river connectivity and plan for national measures; Creating public awareness and reaching out to local groups within the project area to secure support for the conservation of the target species. Specific actions to achieve the conservation objectives will include: A thorough inventory of the project area to obtain comprehensive and up-to-date information on the status of the target species and their habitats; Direct restocking of selected river sections with the target species; Restoration of a gravel river bed in a selected river section; Removal of two barrages and construction of a fish pass to reduce river fragmentation; Evaluation of conservation activities based on monitoring of the river sections where they will take place; Focusing attention on the issues of longitudal river connectivity, river fragmentation and rheophilic fish species conservation through the creation of forums for extensive discussions with national and international experts, and the production of guidelines on fish passes; Dissemination of project results through a layman’s report and specialised scientific publications; and Securing of public involvement and support through a set of communication activities aimed at both specialist and lay audiences. Expected results: The main expected result is the improved conservation status and strengthened populations of the target species, and the improved conditions in selected river stretches in the Danube river basin. Other results will include: Comprehensive and specific scientific information covering populations of seven species of fish and invertebrates in 30 sites with a total area of more than 45 000 m2 in at least 14 Natura 2000 sites; Surveying and assessment of at least 10 existing barriers in three Natura 2000 sites, with a proposal for making them passable for fish; Development of guidelines on requirements for fish passes with a view to their legal adoption at a later stage; Restocking of six fish and one mollusc species in selected locations in two Natura 2000 sites: at least 200 individuals of Cottus gobio, 5000 individuals of Rhodeus amarus, 800 individuals of Sabanejewia aurata, 1 000 individuals of Gobio kessleri, 200 individuals of Gobio uranoscopus and 400 individuals of Unio crassus; Restoration of at least 200 m of the Rusenski Lom river with a suitable bottom substrate, ensuring suitable habitats for Gobio keslleri and Barbus meridionalis; Construction of a fish pass to connect a 30 km section on the Rusenski Lom river; Removal of two barrages on the Rusenski Lom within the Lomovete Natura 2000 site, thereby reducing river fragmentation and reconnecting at least 10 km upstream and 10 km downstream of each barrage; Publication of project results in scientific journals; and A public awareness campaign that reaches 15 000-20 000 people through a range of channels and activities. The project will also involve volunteers (at least 30) in restoration actions.