Because of the lack of information on the genetic structure of fishes on the Belgian Continental Shelf, the Laboratory of Aquatic Ecology of the Katholieke Universiteit Leuven initiated a large-scale survey of the genetic structure of selected marine animals in 1992. Species were chosen on the basis of their abundance and role in the food web (gobies of the genus Pomatoschistus), as ecological indicator (parasites of the flatworm genus Gyrodactylus) or their significance for fisheries (European eel and sole). The most discrete genetic structure is shown by the inshore goby P. microps, which differentiates in estuarine populations along the coast (stepping stone model) (Gysels and Volckaert, in prep). Similar to most marine organisms, the gobies P. minutus and P. lozanoi do not differentiate strongly on a large scale as measured with allozyme markers, but show evidence for selection on an inshore – offshore gradient as measured with allozymes (P. lozanoi) (Stefanni and Gysels, submitted; Gysels et al., submitted) or a metapopulation structure as measured with microsatellite markers (P. minutus) (Pampoulie and Volckaert, in prep). The results have been used over the past years by the Working group on eel (EIFAC/FAO). Fisheries management of eel was optimised by introducing a marine perspective and the isolation-by-distance genetic structure. Expertise of the Laboratory of Aquatic Ecology has also been shared with ICES at the annual meeting (Brugge, 2000), with the Belgian and regional government, with the EU (expert evaluation), the media (TV appearance on exotic species in Flanders; radio interview on transgenics) and the public (voluntary teaching to high school pupils and the public).