Stone crayfish – Kustošak 2021

“Stone crayfish – Kustošak 2021” is a research and educational project of the Crustacean Section, with the aim of estimating the distribution and population status of stone crayfish in the Kustošak stream in Zagreb.

Stone crayfish (Austropotamobius torrentium (Schrank, 1803)) is a native species of freshwater crayfish widespread in Central and Southeastern Europe. This species is sensitive to changes in habitat so any anthropogenic impact puts stone crayfish populations at risk. The stone crayfish is an endangered species, protected by national and international laws. In recent years, a significant decline in the number of crayfish populations has been observed due to habitat destruction, canal construction, declining water quality, water pollution, climate change, and the presence of invasive alien species and the pathogens they carry.

The Kustošak stream is located within the Medvednica Nature Park, where the population of the stone crayfish is extremely rich. A large part of the stream passes through populated areas where the living conditions of crayfish are not so good. In addition, the stream itself has been hydromorphologically altered in some parts which can negatively affect crayfish populations. Therefore, we believe that the project is extremely important for maintaining a stable population of crayfish in the City of Zagreb because with the collected data we will be able to assess the population in the Kustošak stream, which in turn will serve to develop a management plan for this species.

Also, the project will contribute to raising awareness about the importance of protecting local biodiversity, which is an important factor in the self-sustainability of the local ecosystem, and thus the quality of life of the local community.


At the beginning of September 2021. The Crustacean section successfully conducted the field part of the research for seven days. We used the mark and recapture method to estimate the size of the stone crayfish population in the Kustošak stream. Along the way, we collected data on the state of the population (sex ratio, age structure, condition status, etc.)

We would like to thank the elementary school Sesvetska Sopnica, the students of additional biology classes, and professor Marina Petrin Horvatić for participating in the project.

We also thank out donors, the Institute for Medical Research and Occupational Health, Zagreb, and the Faculty of Food Technology and Biotechnology, University of Zagreb:

  • The results of ph, EC, and analysis of the content of anions, cations, and metals in water samples from the Kustošak stream, Zagreb, were provided by the Institute for Medical Research and Occupational Health in Zagreb.
  • The results of measuring ammonium, COD, nitrate, nitrite, total nitrogen, and total phosphate in water samples from the Kustošak stream, Zagreb, were provided by the Laboratory for Water Technology of the Faculty of Food Technology and Biotechnology, University of Zagreb.

We invite all interested students to participate in the project and contact us by e-mail: – Anita Tarandek, project manager – Crustacean Section mail


The project is co-financed by the Student Center in Zagreb and the Department of Biology, Faculty of Science in Zagreb