Biology and conservation of the European mudminnow (Umbra krameri Walbaum, 1792): an update of the monograph 30 years after the first international workshop

During the three decades following the publication of the first comprehensive monograph on the European mudminnow ( Umbra krameri Walbaum, 1792), knowledge of the species’ biology, distribution, genetics, ecology, and conservation has expanded substantially. In several countries, a dynamic distribution pattern has become apparent, with many local populations seemingly disappearing while new populations continue to be documented. However, many of these newly recorded occurrences likely represent previously overlooked remnant populations rather than genuine range expansions. Despite the uncertainty associated with detectability, the overall distribution pattern of U. krameri clearly reflects a large-scale process of range contraction and habitat fragmentation across most of its native range. Recent phylogeographic and population genetic studies have fundamentally improved understanding of the species by revealing pronounced drainage-based structuring, limited contemporary gene flow, and the existence of distinct evolutionarily significant units (ESUs). At the same time, the development of genomic resources, complete mitogenome assemblies, and environmental DNA (eDNA) approaches has created entirely new opportunities for monitoring and conservation. Numerous studies have also advanced knowledge of habitat use, trophic ecology, population dynamics, and conservation management, while conservation breeding and translocation programs have been initiated in several countries across the species’ range. Considering the threats affecting the species, together with the documented population declines and numerous local extinctions, its current IUCN Red List status should be reassessed and upgraded from Vulnerable to Endangered, or possibly even Critically Endangered.