Saving European weatherfish, a swampy business

Once widespread in Flanders (northern part of Belgium), the European weatherfish ( Misgurnus fossilis L., 1758) has been fading away since the 1950s and has reached a critically endangered status. To save this species from extinction, a Species Protection Plan was launched in 2021 focussing on a regional wide innovative eDNA survey, habitat restoration and genetic strengthening of the relic populations by means of a captive breeding program financially supported by LIFE (B4B). a regional wide innovative eDNA survey, habitat restoration and genetic strengthening of the relic populations by means of a captive breeding program financially supported by LIFE (B4B). Although a climate change induced shift in general water management - with attention for more ecologically driven river discharge dynamics (Eflows), rewetting and improving lateral connectivity - provides the right momentum, the road to recovery for this species remains bumpy. On the good side, the species distribution in Flanders seems a bit less dramatic since the eDNA campaign revealed 14 more relic populations, bringing the total currently to 23. Also the breeding program started to pay off with a production of ca. 100.000 individuals in 2025 and the first proof of subsequent natural reproduction in at least one population. On the other hand, classical fishery in most investigated relic populations had a very low success rate, potentially pointing to very low densities. Because of the high demand by different users for the little remaining open space, also habitat restoration remains very challenging in Flanders. Even within the nature conservation sector, the objectives are diverse and sometimes incompatible, leading to delays or even failure to initiate certain restoration projects. Last but not least, the settlement and spread of invasive oriental weatherfish species brings with it new threats and challenges. All the more reason to pool our knowledge and expertise at a European scale, for which SWAMP (Specialist Weatherfish Action and Monitoring Partnership) was recently established. Only by joining forces can we save this enigmatic species from fading further into oblivion (Suppl. material 1).