Larval fish production in the tidal River Elbe 1985–1986

In 1985 and 1986 ichthyoplankton composition was studied during seven sampling series at 37 stations along the tidal Elbe and its tributary rivers between Hamburg harbour and the North Sea. The highest larval density was observed in May and April. No, or very few, larvae occurred from late summer to early spring. Smelt (59% on average of all samples) and twaite shad (20%) dominate in the freshwater region. Herring/sprat (17%) dominate in the estuary. All major spawning grounds are located along the southern shore. Smelt spawn further upstream 1 month earlier than twaite shad. Three percent of all larvae found were flounder. Most of them occurred upstream from the estuary in the R. Este and in other tributary rivers. It is not clear whether flounders are able to spawn in freshwater. Attention is drawn to the fact that an unknown but probably very high percentage of the ichthyoplankton is entrained by local power plants.