Migration of bream between the main channel and floodplain lakes along the lower River Rhine during the connection phase

Abstract

Mature bream (>30 cm L F ) dominated the fish communities in floodplain lakes along the lower River Rhine in The Netherlands, in terms of biomass, in all lakes at all times. In some lakes bream made up 99% of the total fish biomass. While immature, medium-sized bream (10-30 cm) and white bream and roach were abundant in the main channel of the river, these species were almost absent from the floodplain lakes. Inundation of the floodplains did not lead to spatial homogenization of species and length distributions. Small bream (<10 cm) left the floodplains to become resident in the main channel until maturity. Once mature (c. 30 cm), they returned to the lakes during the next inundation and stayed there. Mature bream that moved into the lakes were significantly smaller and had a lower condition than the resident bream. Turbid clay-pits were probably important sources of bream for the lower Rhine and the recruitment of the 0+ year group of bream to the riverine population was influenced by their discharge pattern. 2001 The Fisheries Society of the British Isles

Movement of fish between a river and its backwater: diel activity and relation to environmental gradients

“…Chub is usually observed to migrate mainly at night (Lucas 2000), with peak between 22.00 and 05.00 h (Prignon et al 1998), behaviour we observed in movements out of the backwater. In contrast to reports from the lower Morava (Copp & Jurajda 1999) and elsewhere, e.g., for common bream (Molls 1999;Grift et al 2001), we observed no obvious size-dependent migratory activity of the species.…”

“…Intensive two-way movements of fish were observed in the short 'r-b' connection between the main channel of the River Morava and the Kurfu¨rst backwater, mainly during spring high water levels. This coincided with the spawning periods of the main species observed, and in general resembles the lateral spawning migration reported elsewhere (Welcomme 1985;Molls 1999;Grift et al 2001). The considerable decrease in the water level between 16 and 26 May coincided with reduced fish movements of all fish species through the 'r-b' connection.…”

“…All the main species we observed probably spawned in the backwater, based on the numbers of young larvae captured in a related study (E. Hohausova´, unpublished). However, more fish in spawning condition were observed to leave the backwater than to enter it, apart from perch, which is in contrary with Molls (1999) and Grift et al (2001) findings, who observed various species entering connected backwaters for spawning. This could suggest that fish move into the river to seek other spawning areas due to protracted spawning (possibly bleak; Barusˇ& Oliva 1995) or due to lower suitability of the backwater for spawning (roach, chub).…”

“…Although attention is regularly devoted to migratory fish (Baras 1997;Povzˇ1988), the movements of species, considered as nonmigratory, have received less study until recently (Manteifel et al 1978;Schmutz et al 1995;Clough & Beaumont 1998;Lucas et al 1998;Prignon et al 1998). In most of the studies, movement along the longitudinal river profile is targeted (Schmutz et al 1995;Jungwirth et al 1998); however, lateral movements of fish between the river system water bodies have received much less interest in Europe (Bouvet et al 1985;Kwak 1988;Baade & Fredrich 1998;Molls 1999;Grift et al 2001). In Europe, some attention has been devoted to the importance of connectivity to the maintenance and restoration of floodplain ecological function (Amoros & Roux 1988;Schmutz & Jungwirth 1999).…”

Assessing the health of European rivers using functional ecological guilds of fish communities: standardising species classification and approaches to metric selection

“…However, many species exhibit lateral migration behaviour between main river channels, side channels and floodplain waters, especially in lowland rivers (Aarts & Nienhuis 2003). The status of these species gives an indication of the morphological condition of the river channel and its connectivity with the active floodplain (Welcomme 1979;Grift, Buijse, Breteler, Van Densen, Machiels & Backx 2001;Aarts, Van Den Brink & Nienhuis 2004). Therefore, any scheme to classify migration should reflect the overall connectivity of a river system and include scope for classification of lateral migration requirements of floodplain species.…”