[Fish population of two navigable canals [in Belgium]]
1995
Gerard, P. (Ministere de la Region wallonne, Gembloux (Belgium). Direction Generale des Ressources naturelles et de l'Environnement. Station de Recherches forestieres)
Fish population estimates were performed in two Belgian canals, in order to assess the impact of the recreational fishery on the fish community. In the "canal Charleroi-Bruxelles", a recent modification of the locks, consecutive to the cessation of the navigation, allowed the practically complete draining of the reaches and the catch of a very large portion of the fish community; the four estimates in this canal covered a total area of 9 hectares. In the "canal Ath-Blaton", estimates were carried out by trawling a seine across the whole section of the canal; the twelve estimates were based on three successive fishings and cover a total area of 2.7 hectares. The fish community of both canals involves 15 fish species. The total fish density is rather high and ranges between 9000 and 56000 individuals per ha. These values correspond to a biomass ranging between 250 and 900 kg per ha, according to the reach. The roach represents about 80 per cent of the total number of fish (50 per cent of the total fish biomass) and the bream 4-8 per cent of this number (25-30 per cent of the biomass). The predators represent less than 5 per cent of this biomass.
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