The Case of the Upper Drina: An ecological integrity study

This study, "The Case of the Upper Drina: Ecological Integrity as a Prerequisite for Preserving a Unique Aquatic Core Habitat of Global Significance," is a scientific position paper, serving as an urgent appeal from the international scientific community to protect one of Europe’s most vital and intact river systems from extensive hydropower development.

The Upper Drina Basin (UDB), located between Bosnia and Herzegovina and Montenegro, is considered a "centrepiece" for the global survival of the Danube salmon (Hucho hucho). Despite its immense value, the region is under acute threat:

• Development plans: Over 25 new hydropower plants (HPPs) are planned within the first 50 km of the UDB, including the Buk Bijela project, which features a 55m high dam and an 11km long reservoir.
• Fragmentation: These projects threaten to submerge vital spawning grounds and disrupt the longitudinal and lateral connectivity essential for migratory fish to complete their life cycles.
• Inadequate protections: Only about 5% of the Drina River Basin is currently protected, far below European averages, leaving high-value biodiversity hotspots vulnerable.

The Scientific Criticism

The paper highlights several critical flaws in current development approaches:

• Ineffective mitigation: The study asserts that hatchery stocking cannot compensate for Danube salmon population loss, as hatchery fish often exhibit reduced survival rates and can erode the genetic fitness of wild populations.
• Underestimated impacts: Current environmental assessments often fail to account for cumulative and transboundary impacts, particularly given the interconnected nature of the Drina and its tributaries.
• Threat to endangered species: The basin is home to 22 fish species, 13 of which are protected under the EU Habitats Directive or the Bern Convention, underscoring the urgent need to preserve remaining intact habitats.

Read the full study here.