La reproduction des poissons de nos rivières

This paper gets a general view of the main aspects of the reproduction biology of freshwater fishes living in Belgian Rivers. In a first step, the reproductive periods of 14 species, their control by photoperiod and temperature as well as generalities about the spawning behaviour are considered. In a second step, more detailed attention is drawn on to three species : the grayling Thymallus· thymallus ; the barbel Barbus barbus and the bream Abramis brama. Other fish species are also briefly considered : roach, carp or perch. The breeding periods of the 3 species during the year 1993 and their spawning sites are presented, followed by a detailed description of sexual behaviour. As a general rule, each male grayling spawns with one female. In some cases, sneaking males can take part in the spawning act too. As far as barbels and breams are concerned, groups of males spawn with one female and reproduction resorts to the arena system respectively. The interest of scientific researches focused on reproductive behaviour as well as conservation and restoration of the spawning sites are discussed. Two examples are commented : management of salmonids Rivers and experimentation on artificial spawning grounds.