Pontic shad (Alosa immaculata) migrating upstream the Danube river and larval drift downstream to the Black Sea in 2016

Abstract

The genus Alosa is present only in the northern hemisphere of the earth with four species living in North America and others five in Europe, from which Pontic shad (Alosa immaculata) is subject of present study. Migration of shad depends of the environmental drivers such as increasing spring water temperature and river flooding. In 2016, both factors favoured an earlier start of shad migration in February with peak of spawning run in April, and ended in mid of May. Afterwards the size of catches and market demands no longer motivated fishermen to fish and sell Pontic shads. The 2016 catch of 386 t fitted in the multiannual 10-11 years cyclical catches. Reproduction success was estimated by Larval Abundance Index (LAI) standardized as Catch per Unit Effort (CPUE) by number of larvae per 100 m3 filtered water volume. Relative abundance of drifting larvae in 2016 compared with other 6 previously years showed that average LAI varied widely (2-1,252 larvae per 100 m3) with an average of 84 larvae/100 m3 which was ranked in regular reproductive success.

Keywords

• Danube River
• Pontic shad
• adult’s migration
• larva drifting in 2016