Migration Pattern And Recapture Rate Of Salmon Salmo Salar L. Stocked Into The Rivers Of The Southern Gulf Of Finland In The Baltic Sea

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Recapture rate, time and place of salmon released by Põlula hatchery (Estonia) have been analysed. The fish at the age of 1 or 2 years (mainly smolts) marked by external (Carlin) tags or fin clipping were released in April-May. The males ascended to spawn mainly in the age of 2 sea summers, females after 3 sea summers, the proportion of older fish was small. There was a shift towards earlier maturation (1 sea summer fish) among stocked by Põlula male salmon compared to wild or stocked by Narva hatchery (Russia) fish in the same region. The success of stocking of a particular year class of salmon can be estimated after three-four years. The recapture rate of tagged salmon varied between the rivers and years, but was generally low (0-5%). Besides smolt size the time interval between tagging and stocking may influence the survival and thus the recapture rate of tagged salmon. The released by Põlula hatchery salmon are mainly caught in the Gulf of Finland, but during second year of sea life significant part (45%) is caught in the Main Basin of the Baltic Sea.