Restocking of European eel as a measure of recovery of endangered species and preservation of natural diversity.

European eel is a critically endangered species and its distribution reaches outside of the European Union territories, including Narva River Basin District (Narva RBD). There have been no cross-border estimates done for the stock of European eel in the whole Narva RBD, as this fish species is not studied and monitored based on a similar methodology in Estonia and Russia. Knowing the exact escapement of silver eels from Narva RBD is essential for judgement of the species’ welfare and planning further eel management actions, as the whole eel stock of Narva RBD is based on restocking. Practices for collecting and sharing of data about European eel on Russian and Estonian side are not harmonised. In addition, a stock assessment about eel in the Russian waterbodies of Narva RBD till today is basically non-existent. European eel is an important fish species for both commercial and recreational fishery in Narva RBD. Without cross-border stock assessment it is impossible to plan and implement the stock management of European eel in Narva RBD. Stock assessment of European eel in the whole Narva RBD would be a valuable contribution to the European-wide stock assessment of European eel. Project approaches these challenges by using novel ways to estimate the abundance of eel on the waterbodies on both sides of the border. It will be for the first time that the stock of assessment of European eel is simultaneously carried out in a river basin district shared by Russia and Estonia using the same methodology. A novel method of using an enclosure fyke net system with 1 ha surface area will be applied on all of the waterbodies selected on both sides of the border. The enclosure fyke net system will be the main tool of the project in the estimation of eel abundance. The novel enclosure fyke net methodology will be used on the fieldworks during the three-year project period. Right now an existing practice of eel specialized methodology and research development are absent on the Russian side of Narva RBD. Russian scientists will adopt the same novel methodology on their waterbodies in cooperation with Estonians. Usage of the same methodology and data collection technique by both Russian and Estonian researchers, makes a joint stock assessment possible. Using the knowledge obtained during the project, a better cross-border management of the eel stock will be possible in future. Knowing the relative stock abundance and origin of eels inhabiting Russian and Estonian side of Narva RBD, a more accurate management of the eel stock in the transboundary Narva RBD as well as more precise measurement of the restocking efficiency is possible. If the new knowledge about restocking efficiency and project results approve and require, the project could result in an eel restocking programme for the Narva River and Lake Peipsi that would add a clear value to the local fishing sector. Assessment of the eel stock in the whole Narva RBD would be impossible without cooperation between Russian and Estonian side. Because Narva RBD is a transboundary water system, it can be researched only together with Estonian and Russian researchers, because waterbodies on the Russian side of the RBD are out of reach for Estonian researchers and vice versa. This project helps to fill the knowledge gap of eel distribution and stocking-densities in the north-eastern part of Europe, most importantly in Narva RBD, which is shared between the Republic of Estonia and the Russian Federation. The data on silver eel escapement as well as yellow eel production in the Russian waterbodies of Narva RBD is necessary for a precise and reliable stock assessment for the whole region. This project would be the first time a joint assessment of eel stock between Estonian and Russian researchers is attempted.

Improved awareness of the stock status and escapement of eel in the region would contribute directly to the increased capacity in environmental protection for joint water assets, including fish. As eel is an highly endangered species, a special and novel way of stock assessment helps to preserve and use the eel stocks of Narva RBD sustainably. Knowledge of sustainable management of the species helps to improve the status of eel, supports the biodiversity of joint natural assets and helps to conserve eel population for future generations.