LATVIA
Latvia’s ďŹ rst ďŹ sh pass reconciles the needs of ďŹ sh with those of the local community
Reopening of RÄŤva river for salmonids and river lamprey The RÄŤva is a 53 km long river owing through the western part of Latvia. Its source is the VilgÄ les lake and it empties straight into the Baltic Sea. Approximately half the riverbed has been straightened but despite this, this beautiful river still hosts plenty of habitats suitable for the reproduction of salmonids and lampreys. However, only a limited number of the potential spawning habitats is used. For more than a century the upstream migration for ďŹ shes in this river has been blocked by the remains of a dam belonging to a paper mill which has never been ďŹ nished. Today, the remains of this dam form a picturesque waterfall and serves as the foundation for a wooden bridge which is a popular sight for tourists. Apparently, its popularity among tourists is the reason why an idea to remove this barrier faced strong opposition from the local community.
H
owever, within the INTERREG RETROUT project, a solution for this issue was found. If the obstacle could not be removed, then the fish must be guided around it. To provide a safe route for upstream migrating fishes a near-natural fish pass/fauna passage is currently being built around the dam. And yes, after completion this will be the first near-natural fish pass constructed in Latvia. The pass will
look like a small natural stream thus providing migration possibilities not only for salmonids but also for such relatively weak swimmers as river lamprey and eel. How do researchers know that this fish pass will be used by upstream migrating fish? Well, it cannot be guaranteed, because nature does not always respond to human activities in the way expected. However, the chances are bright. Firstly,
the results of electrofishing in the monitoring site located just downstream of the dam confirm the reproduction of salmon, sea trout, and river lamprey in the currently available part of the RĆŻva. Moreover, the existence of populations of brook lamprey and brown trout found in survey sites upstream from the dam suggests that the river is well suited to sea trout and river lamprey. Above all, however, is it even possible that such a beautiful
river is not suitable for migratory fishes? Let the journey begin!
For more information, contact: Didzis Ustups National Institute of Food Safety, Animal Health, and Environment (BIOR) Tel.: 371 6761 2409 didzis.ustups@bior.lv www.bior.lv
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07/10/20 8:25 PM