Fertility of the smelt Osmerus eperlanus (Linnaeus, 1758) of the Curonian Lagoon of the Baltic Sea

The Curonian Lagoon is located in the southwestern part of the Baltic Sea and is geographically under the administrative control of the Russian Federation and the Republic of Lithuania. The water body is connected to the Baltic Sea by a narrow strait in the northern part located in the Republic of Lithuania. About 50 species of fish live in the lagoon, of which 25 species are of commercial importance. The European smelt Osmerus eperlanus is a migratory species; it spawns in the rivers of the Curonian Lagoon, the main spawning grounds are in the Neman, Deima, and Matrosovka rivers. Most of their life smelts live in the Baltic Sea where they fatten up. The spawning part of the smelt population is caught in the Curonian Lagoon. In commercial catches, smelt are represented by individuals from 1 to 6 years old, for the most part, individuals mature at the age of 2 to 3 years. The research used reproductive figures for smelt from 1989 to 2001. The weight of females varied from 8.3 to 113.4 g, averaging 47.2 g. The absolute individual fertility of smelts varied from 3,300 to 93,100 eggs averaging 32,000 eggs. The relative individual fertility averaged 900 eggs/g. The gonadosomatic index (reproductive effort) averaged 0.27, the egg diameter varied from 0.59 to 0.98 mm averaging 0.77 mm. It can be concluded that the reproductive performance of the European smelt O. eperlanus exceeded the reproductive performance of smelts in other water bodies of the northwest of the Russian Federation. The smelt fertility study in the Curonian Lagoon showed that the reproductive capacity of the species is in good condition, which is apparently due to good trophic conditions in the feeding area, the Baltic Sea.