Handbook of the Fishes of Wallonia, southern Belgium. Distribution, Ecology, Ethology, Population abundance, and Conservation

The present report is a synthesis of a fifteen-year investigation on the Freshwater fishes of Wallonia. The forty one indigenous species recorded (see table 3) can be classified as follows with regards to the status of their populations: i) 7 anadromous migratory species (Petromyzon marinus, Lampetra fluviatilis, Acipenser sturio, Alosa fallax, Alosa alosa, Coregonus oxyrhincus, Salmo salar) are locally extinct; ii) 4 species were recorded in small numbers (Platychtis flesus, Salmo trutta trutta, Lota lota, and Leuciscus idus) and are extinct as reproductive populations; iii) Misgurnus fossilis, Cobitis taenia, Leucaspius delineatus and Rhodeus sericeus are rare, very locally distributed and highly endangered species for which severe conservation measures are urgently needed (legal protection, prohibition of angling, natural reserves, protection of the habitats and biotopes); iv) all the litophilous species (Alburnoïdes bipunctatus, Barbus barbus, Chondrostoma nasus, Phoxinus phoxinus, Leuciscus cephalus, Leuciscus leuciscus, Thymallus thymallus, Salmo trutta fario, Cottus gobio, and Lampetra planeri) are suffering a strong decline of their populations especially in the heavy polluted Schelt basin and in several area in the more preserved river Meuse basin as well. The conservation of these species could be achieved by limiting the incidence of water pollution, eutrophication process and physical alterations of the habitats, improving some fishing regulations (legal sizes, closed seasons), developing methods of artificial reproduction and propagation, establishing integral reserves in any aquatic biotope with a relict or highly ecological representative populations of fish community; v) Most other species have locally desappeared or declined due to chronic acute pollution but on the whole they are still widespread all over the country and even rather common in their particular habitats; they do not require any special conservation measures, except those relating to a) the maintenance of a sufficient water quality and habitat convenience for reproduction and to b) an improvement of the fishery management, especially regarding the efficiency of restoking