Endangered fishes of the River Morava (Czech Republic)

Summary

This study provides an “up-to-date” assessment of the condition and status of the fish fauna in the entire Czech stretch of the River Morava (River Danube basin), with special attention paid to species regarded as rare or endangered. The present ichthyological survey shows that 49 of the aforementioned 62 species were recorded in the Czech part of the Morava River system. A further 9 species are known to have occurred historically; however, these have not been documented in this part of the river in the recent past. Species richness in the river was seen to increase as one moved downstream, from 6 to 35 species. The lowest section of the river was also enriched by migrants from the River Danube. Ten of the species found are included in the Czech red data list and 12 are protected under Czech legislation. In addition, a further 6 species found seem to be currently very rare in the River Morava, with a rapidly declining stock, and yet are not included in any official list of endangered fishes or protected legislatively.

Channel regulation and fragmentation by weirs, has had a major impact on rheophilous species. Channelization destroys the natural connectivity existing between the river and its flood plain and has deleterious effects on phytophilous spawners. Thus channelisation would seem, apart from water pollution, to be the most serious cause of decline in the species diversity of fish assemblages in the River Morava.