LIFE NATURE | LIFE AND FRESHWATER FISH OVERCOMING RIVER BARRIERS Creating blue corridors in Poland Many fish species are highly mobile, spawning in one place and feeding in another . Some even travel thousands of kilometres, migrating from salt water to freshwater habitats or vice versa . LIFE projects in Poland are constructing so-called blue infrastructure that allows fish to keep on moving . tlantic salmon (Salmo salar) spend most of activities (e.g. road-building, development, log- Atheir adult life in the salty waters of the At- ging, etc.). The populations separated in this way lantic Ocean or the Baltic Sea. However, they return are weakened, reduced or even eliminated due to to the freshwater streams where they once hatched a lack of genetic diversity and inbreeding. Opening to spawn. Young salmon stay in their native river for up new passageways or wildlife corridors allows up to four years, before they slowly begin their jour- an exchange of individuals between populations, ney back to the ocean. There they feed and grow strengthening them and moderating the effects of into adults that, once they are ready to spawn, re- habitat fragmentation. turn to their native river to begin the cycle anew. The project teams are also building fish passes to For spawning, salmon need large stretches of clear migration routes along the Ina and Rega rivers gravel beds where they can dig out nests (“redds”) and their major tributaries. Although there are good and bury their eggs; and the young salmon need natural spawning sites further upstream, the fish clear, cool, well-oxygenated and fast-flowing rivers cannot currently reach them, as they are hampered and streams to develop and grow. The projects have constructed fish passes for Atlantic salmon Dwindling populations As in many parts of the EU, the Atlantic salmon populations of the Ina basin in Western Pomerania and the Rega River in north-western Poland have dwindled over recent decades. As a result since 2005, the Rega has been restocked with Atlantic salmon and 121 440 fry of this species have been put into the river. Since existing spawning grounds are not large enough to restock salmon it has been necessary to clear spawning channels and create Photo: LIFE10/NAT/PL/000654/Joanna Pawelec/Elżbieta Typańska Pawelec/Elżbieta Photo: LIFE10/NAT/PL/000654/Joanna appropriate spawning grounds. Since 2011 and 2012, two LIFE projects (LIFE10 NAT/PL/000654 and LIFE11 NAT/PL/000424) are supporting the restocking effort. They aim to conserve and im- prove the biodiversity of the water ecosystems in target areas, which encompass several Natura 2000 sites, mainly by creating a blue wildlife cor- ridor interlinking sites. Reconnecting isolated sites In the Ina and the Rega basins populations of many species have become isolated as the result of human 47.