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The collected data confirm: eels are very mobile in the Narva river basin

In the period 2019-2022, the project "Restocking of European eel as a measure of recovery of endangered species and preservation of natural diversity" (ESTRUSEEL) was carried out in the Narva river basin as a part of the Estonian EU external border programme 2014-2020, during which data on eels were collected in the transboundary waterbodies of Estonia and the Russian Federation.

An experimental enclosure fyke net system with surface area of 1 ha and small fyke nets set in line were used as survey fishing gear. In total, fishing was carried out at 51 sampling spots in Estonia and in 52 sampling spots on the side of the Russian Federation, during which 86 eels were caught. All eels were analyzed and various parameters recorded. The otoliths of the caught eels were microchemically analyzed to determine their origin and possible movements in the Narva river basin.

71% of the samples were collected from Lake Peipsi, the rest from the Narva Reservoir, Narva River and the Rosson River. Collected information showed that eels migrate throughout the Narva river basin. The majority of the analyzed specimens left the original water body of restocking within the first two years after settlement, which means that the eels are not subject to fishing pressure in the given water bodies, making the migration towards Baltic sea more probable.

Unfortunately, based on the results of the project, it was not possible to estimate the exact amount of the eels in each restocking water body which are such early migrants, but the results of the survey fishing showed that a significant population of eels reside in Lake Peipsi, which includes individuals in all development stages. Survey fishing on the Narva River and Narva reservoir confirmed that the restocked eels are able to find their way to the sea, among the catch there were specimens deriving from all original restocking water bodies located in the Narva River Basin (Võrtsjärv, Saadjärv, Kaiavere Lake, Vagula Lake, Kuremaa Lake).

In the future, it is necessary to find a way to estimate the number of migrating eels in the upper and lower reaches of the Narva River in order to get a more accurate overview of the potential biomass of migrating eels. The results of this project also show that a solution is needed for the eels to bypass the Narva hydroelectric power plant unharmed, as at the moment, the restocked eels must inevitably pass through the turbines of the hydropower station to reach the sea.

The activities of the project and the eel biology were introduced to the public through various events and media channels. A total of 53 people from Estonia and the Russian Federation participated and were directly involved in majority of the project's activities - researchers, fishermen and supporting staff of research institutions.

A total of 502 students and teachers participated in the seminars held in local schools, 669 persons in the seminars aimed at the public. Through other media (newspapers, magazines, internet platforms), information about the project and the status of eel in the Narva river basin reached more than 181,200 people. The project's social media account (Twitter) had a total of 103 followers.

Project report is available at: https://pk.emu.ee/en/structure/hydrobiologyandfisheries/research/projects/international-projects/estruseel/. This publication has been produced with the financial assistance of the European Union. The content of this publication is the sole responsibility of Estonian University of Life Sciences and can under no circumstances be regarded as reflecting the position of the Programme or the European Union.

The ESTRUSEEL project was implemented under the European Neighbourhood Instrument and co-financed by the European Union. The total budget of the project is EUR 361 856,00 including the Estonian EU external border programme co-financing in amount of EUR 325 670,40.