FISH SPECIES OF THE LOWER ZEESCHELDE (BELGIUM) - A COMPARISON WITH HISTORICAL CHECKLISTS

In the 19th century approximately 40 fish species (excluding freshwate r species) were recorded in the lower Zeeschelde between the Dutch/Bel gian border and Antwerpen. In comparison with the 19th century and the first half of the 20th century the total number of fish species in th e Beneden-Zeeschelde has decreased considerably. The present checklist (1991-1993) of fishes of the lower Zeeschelde (excluding freshwater s pecies) contains only 26 species. The fish community is composed of ma rine species (13), catadromous species (3), estuarine residents (9) an d one anadromous fish species. Besides, 6 freshwater fish species have presently been recorded. The distribution of diadromous fishes, estua rine residents and freshwater fishes is probably greatly affected by l ow oxygen levels in the lower Zeeschelde, whereas the disappearance of adventitious marine species is probably also the result of anthropoge nic effects on a much wider geographic scale. A comparison was made wi th recent and historical checklists of fishes of the Westerschelde and the Oosterschelde (the Netherlands).