28.06.2021, 14:42h
After months of preparation, the extraction of invasive fish species to begin at Krka NP
This past weekend, the local population, the truest fans of the natural values of the Krka River, caught more than 50 pike, an invasive fish species
The endemic and rare freshwater fish fauna makes the Krka River a nature monument of the highest national and international importance from the ichthyology perspective. That is why in 2020, Krka National Park launched the project “Distribution and state of the population of target species of freshwater fish in Krka National Park”. The project is aimed at collecting additional information about the freshwater fish community, determining the habitats and distribution of target species, and determining the zone areas of the ecological network. The project envisages the application of specific conservation measures for these species, and includes indicators of the success of implementation of those measures.
Due to the introduction of invasive species that threaten the indigenous river endemic species, a Protocol for the extraction of invasive species has been developed. In line with the Protocol, last weekend some 30 local fishermen were invited to fish for pike along the banks of the Krka River. We would like to thank these enthusiasts for recognising the importance of this campaign and accepting our invitation, as through their participation they have shown that they understand the importance of protection of the river ecosystem. The first results are already expected this autumn. Considering that this is a long-term project, its success depends on organised, continuous extraction activities. The data collected from the fisherman, including site of catch, species, length, weight and number of individuals, will be analysed as one of the implemented methods for monitoring the state of the ichthyofauna.
Before the start of project implementation, the Public Institute of Krka National Park held a meeting with representatives of the local population, with the participation of the director for the Nature Conservation Directorate and the Department Institute for Environmental and Nature Protection of the Ministry of the Economy and Sustainable Development. The representatives of the local community were informed of the plans of the park for projects concerning conservation, biodiversity and indigenous and endemic species, and their cooperation and support for their implementation was requested. In addition to selective angling, the result of the agreement was that education will be conducted on the importance of monitoring the population size of invasive species, and methods to permanently reduce their numbers. This summer, education will be held by eminent experts who participated in the development of the Protocol, led by Professor Dr. Davor Zanella from the Division of Zoology, Department of Biology, Faculty of Science at the University of Zagreb.
Fish are important bioindicators of the quality of the environment, and the state of their populations and their presence in Krka National Park are indicators of the preservation of the water quality in the Krka River. The Freshwater Fisheries Act (OG 63/19) and the Ordinance on the protection and conservation of Krka National Park (OG 123/19) are strongly directed towards conserving the resources and wealth of biodiversity. Fishing is prohibited in the park, in order to protect the wealth and diversity of the fish community, particularly those species that are not found anywhere else on Earth. We should all be interested in how we leave our ecosystems for the generations to come, and controlled fishing of invasive fish species is a step towards sustainable river ecosystem management.
There are about 28,000 known taxa of fish (Pisces), making this the largest group of vertebrates. There are 31 fish species inhabiting the Krka River, and of these 12 (or 40%) are endemic species. Nine species are endemic to the Adriatic Basin, three are stenoendemic to the Krka River, meaning they are found nowhere else. Exceptional endemic species are the marble trout and soft-mouth trout, while the Illyrian chub and brown trout are most numerous. These species are threatened by organic water pollution, habitat change, fishing, stocking with alien fish populations (threat to the genetic diversity) and global warming.
