Background Fish are unusually active animals, changing their habitats over the seasons of the year with the aim of reaching particular stages of their lifecycle. They reproduce in one place, their fry and young feed elsewhere and adult fish prefer other sites as their feeding grounds. The same applies to winter habitats of particular fish generations. With this in mind, it is therefore important to protect the sites that are crucial to fish existence (spawning grounds, migration routes), as well as to preserve periodical river floods – as it is according to the natural rhythm of ebbs and flows that river ichthyofauna accomplish their lifecycle. Disturbing or breaking this rhythm can (in extreme cases) result in extinction, and, often leads to a reduction in numbers of particular fish species. The Rega basin is a relatively cohesive ecosystem. However, the construction of a high number of hydro-technical structures has caused a significant decrease in its biodiversity. These structures make it difficult, or even impossible, for fish to arrive at their spawning grounds or inhabit appropriate biotopes, located in the upper course of the river. Since 2005, the Rega river has been restocked with Atlantic salmon (Salmo salar) and 121 440 fry of this species have been put into the river. Since the spawning grounds are not large enough to restock salmon it is necessary to clear spawning channels and create appropriate spawning grounds. In the Rega basin there are two Natura 2000 protected sites: the mouth of the Rega river and the Brzeźnicka Węgorza. By clearing the whole area of the Rega basin some wildlife corridors will be created. Objectives The overall project objective is to increase the biodiversity of the water ecosystems protected by the Natura 2000 sites, by linking them with an ecological corridor. The additional objective is to restock the salmon population in the Rega basin. Specific project objectives are: To clear the Rega river and its major tributaries to make them accessible for the fish; To create artificial spawning grounds to increase the number of fish inhabiting the Rega river, and to improve the population of Atlantic salmon; To record the fish migration to identify when and where fish access the spawning sites in the Rega basin; and To create an ecological corridor that will encourage indirect protective measures for the Natura 2000 areas, which for many reasons are now isolated enclaves, with limited possibility to perform various protective actions. Expected results: Clearing of the Rega river and its major tributaries by building fish passes; Creation of artificial spawning grounds and enlargement of the existing ones; Planting of trees along 47 km of the river bank to decrease water temperature; Installation of monitoring devices to keep a record the fish migrating upstream and downstream; and Installation of electronic barriers at the sites where a specific result is expected, i.e. at Rejowice, Likowo, Gryfice and Płoty.