Only four indigenous and six non-indigenous species of fish comprise the ichthyofauna of the Plitvice Lakes. The key species in the Plitvice Lakes watercourses is the Black Sea salmon (Salmo labrax), which is particularly well adapted to the conditions in both streams and creeks, but also in lakes where it grows to impressive sizes.
Unfortunately, recent studies found that the Plitvice Lakes ichthyofauna had changed significantly owing to anthropogenic activities. The changes are mostly reflected in the introduction of alien species which have become dominant in the lakes. In addition to the direct impact of the alien species as competition and predators, the negative impact on the indigenous species is also reflected in the changes in habitat conditions, which have become suboptimal or entirely unsuitable, possibly even lethal for individuals of the indigenous species.
The first project to remove the invasive fish species in the Plitvice Lakes National Park was carried out in 2021, and the activities are still ongoing today. Harvesting activities are carried out every month from April to October.
The project “Removal of Invasive Fish Species in the Plitvice Lakes National Park” has been carried out by the Faculty of Science of the University of Zagreb, the public institution AQUATIKA – Karlovac Freshwater Aquarium and the employees of the Park’s expert service. The main purpose of the project is to harvest the alien species of fish from the Plitvice Lakes National Park watercourses and to re-establish adequate conditions for indigenous species and ensure their survival.