Plitvice Lakes National Park is joining the global campaign to mark World Fish Migration Day under this year’s slogan, “We Are River People“. This event is celebrated every two years in May to raise awareness of the ecological importance of migratory fish species and the preservation of the river ecosystems on which they depend. Migratory fish species are those whose individuals or entire groups migrate to exploit resources such as habitat or food, most often migrating to spawn. According to IUCN data, as many as a third of freshwater fish species worldwide are threatened with extinction due to habitat loss, river fragmentation or barriers on watercourses, water pollution, and climate change. Marking World Fish Migration Day helps to launch global actions to restore river connectivity and protect these key species before it is too late.
Danube Trout and the Bijela Rijeka stream
In response to these challenges, our Park proudly recalls the first removal of artificial barriers on a watercourse in the Republic of Croatia, which was carried out last year on our Bijela Rijeka stream. The main role in this story is played by our native migratory species, the Danube Trout (Salmo labrax), which until a few years ago was almost on the verge of extinction (Figure 1). The Danube Trout migrates to the upstream parts of the watercourse to spawn, and on the Bijela Rijeka stream this vital journey was prevented by artificial barriers, remnants from the past when people used this watercourse for their own needs. To preserve its populations, five years ago we launched a complex, pioneering conservation project that includes the removal of invasive fish species, the restoration of the Danube Trout population through stocking, and the removal of artificial barriers on the Bijela Rijeka stream (Figure 2).
A year after the removal of the barriers, we received confirmation of success and a reward for all our hard work – through monitoring, we confirmed the return of the Danube Trout to the restored streams, where it had not been recorded for almost a hundred years (Figure 3). Although we have removed the barriers on the Bijela Rijeka stream, our work to restore the population of this migratory species is not yet complete. We continue to remove invasive species and restock, and we plan to restore free flows to other watercourses in the Park area.
Figure 1. Danube Trout (Salmo labrax) 
Figure 2. The course of the Bijela Rijeka stream after the removal of the embankment and pipes (photo: Darko Mihalić) 
Figure 3. Danube Trout caught on the restored part of the old stream (photo: David Dianežević)
Get involved!
This year, inspired by the success on the Bijela Rijeka stream, we want to share with our visitors the main messages of this global campaign:
- Migratory fish are extraordinary—some travel thousands of kilometers to complete their life cycles, relying on healthy, connected rivers.
- Free-flowing rivers are essential for biodiversity, climate resilience, and human well-being.
- We are river people—our lives, cultures, and histories are intertwined with the rivers and fish around us.
- Every action counts—from hosting events to sharing stories, we can all be stewards of rivers and fish
We invite you to explore the richness of our rivers and support efforts to preserve free-flowing waterways. Learn more about the global movement on the official World Fish Migration Day website, share your photos and support on social media with the hashtags #WeAreRiverPeople and #WorldFishMigrationDay, and be a voice that protects rivers and the fish that inhabit them!
