Identifying and mapping the barriers on the rivers and streams of Eastern Herzegovina, and assessing their impact on the migration of endangered endemic fish species.
Located within the Republic of Srpska’s jurisdiction, the upper watershed of the Neretva and Trebišnjica rivers forms a vital component of Eastern Herzegovina’s natural heritage. This area is renowned for its unique karst topography, characterised by sinking streams and a remarkable diversity of endemic species.
To harness the waters of these rivers for hydroelectric power, a complex of seven substantial dams, six artificial reservoirs, extensive tunnel systems, and a canal network has been constructed. This infrastructure plays a crucial role in the local economy. However, amidst this development, numerous antiquated barriers—originally erected for irrigation purposes—now serve no practical function yet continue to obstruct the passage of threatened endemic fish species.
Despite significant alterations to their natural state, the rivers and streams of Eastern Herzegovina maintain a high level of endemism. Remarkably, certain freshwater species can adapt by migrating underground, enabling them to thrive in these challenging conditions.
| Project status | Completed |
|---|---|
| Project type | Barrier identification and prioritisation |
| Country | Bosnia and Herzegovina |
| Rivers | Upper Neretva and Trenišnjica watershed, including rivers: Trebišnjica, Sušica, Opačica, Vrijeka, Mušnica, Zalomka, Zovidolka, Ključka Rijeka, Brova, and Bukov Potok |
| Focal species | Paraphoxinus ghetaldi, Paraphoxinus pstrossi, Paraphoxinus metohiensis |
| Organisation | Vrelo NGO |
| Website | Vrelo NGO |
The barriers on the upper watershed of Trebišnjica and Neretva hinder the migration of endemic fish species, notably the Gatacka gaovica, Popovo gaovica, and Trebinje gaovica. These barriers, largely obsolete structures from past irrigation systems, have drastically reduced the available habitat for these species to a mere 7% of their natural range. By mapping and identifying these barriers and assessing their impact, we can pave the way for their subsequent removal to restore connectivity between surface and underground waters, which is vital for the survival of these endemic fishes during their migratory cycles.
The project aims to mitigate the ecological impacts of human activities and foster the preservation of the unique biodiversity in the upper Neretva and Trebisnjica watersheds. By identifying and mapping existing barriers, the project will create opportunities for their future removal, reducing the pressures on the riparian ecosystem, increasing the available habitat for endemic fish species, and restoring connectivity between surface and underground waters vital for their survival. Another key goal is to engage local communities and authorities in conservation efforts, increasing awareness of the impact of barriers and the benefits of their removal. By promoting sustainable environmental practices and management strategies, the project aims to ensure the long-term health and resilience of the Trebišnjica River and its associated ecosystems. Overall, the project aims to contribute to the revitalisation and ecological recovery of the rivers and streams of Eastern Herzegovina, ensuring the survival of its endemic fish species.
The project aimed to identify and prioritise the removal of obsolete barriers in the Neretva and Trebišnjica watersheds in the Republic of Srpska entity of Bosnia and Herzegovina, to restore ecological balance and improve habitats for endemic fish species. It achieved several key outcomes through meticulous planning, research, and stakeholder engagement.
A comprehensive inventory of barriers was developed, mapping ten rivers and identifying 32 barriers, including twelve critical barriers that significantly disrupted fish migration and biodiversity. This detailed GIS-based dataset formed the basis for planning restoration efforts. The project also conducted a feasibility study for the twelve critical barriers to assess the environmental, social, and technical aspects of barrier removal. As a result, six priority barriers were identified as the most suitable for removal based on their potential to deliver significant ecological and social benefits.
Community and stakeholder engagement played a vital role in the project. Workshops, meetings, and a final conference facilitated collaboration among local authorities, scientists, and community members. These discussions ensured consensus on barrier prioritisation and fostered alignment with local and national ecological objectives. Additionally, communication and awareness campaigns, supported by media outreach and promotional materials, enhanced public understanding of the project’s importance and objectives.
Despite these successes, the project encountered several challenges. Fieldwork in remote and inaccessible areas was complicated by vegetation and debris, requiring additional resources such as drones and off-road vehicles. Achieving stakeholder consensus was a complex process that demanded extensive dialogue to balance technical, ecological, and social considerations. Logistical issues, such as limited accessibility due to weather conditions – particularly heavy rainfall and high water levels during the spring of 2024 – also caused delays in data collection.
Overall, the project established a robust foundation for restoring the Trebišnjica Basin’s ecological integrity. By aligning with the EU Water Framework Directive goals and engaging diverse stakeholders, it significantly advanced efforts to protect endemic fish species and revitalise karst river ecosystems. Moving forward, securing funding and ensuring continued community involvement will be crucial to implementing the removal of prioritised barriers and achieving long-term environmental benefits.
The project’s team received a follow-on pre-demolition grant to prepare for the removal of six barriers.
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