Biological characteristics of European smelt (Osmerus eperlanus eperlanus L.) of the Deima River in the Kaliningrad region during spawning migration

Abstract

The rivers of the Curonian lagoon basin (the Neman, Skirvite and Matrosovka rivers) are traditional places for commercial and recreational fishing of European smelt for many decades. Since 2020, commercial fishing for European smelt has been carried out on the Deima River and currently there are already four fishing crews fishing here on an ongoing basis. The spawning migration in 2022 to the Deima River lasted for 19 days and it coincided with the migration to the Neman River. In the Deima River during the study period, the ecological (lake) form of European smelt - dwarsmelt - was not identified, which is typical for the main spawning rivers of the Curonian Lagoon. The size structure of the spawning part of European smelt in the Deima River is similar to the Neman and Matrosovka rivers. The dominance of fishes with a length of 13–14 cm at the age of 3–4 years and a slight increase in the average length of fishes were noted. A comparative interannual analysis of the age structure of European smelt showed the transition of the high-yielding generation to an older age group, which is confirmed by data on the weighted average age. In 2022, females dominated the entire spawning migration, with the exception of a leveling off in the sex ratio in the middle of migration. Despite the identified biological characteristics of the European smelt in the Deima River, it is part of a single population of the Curonian Lagoon and from the point of view of managing waterbioresources it can be considered as one unit of the stock. A potential location for organizing commercial fishing in the Vistula Lagoon basin is the Pregolya River, where European smelt is a favorite object of recreational fishing.