Patterns of drift and power station entrainment of 0+fish in the River Trent, England

Entrainment of 0 + riverine fish (mostly pelagic cyprinids) by a power station intake, and down-river drift over a nearby weir, followed the same pattern, occurring throughout the year and being greatest during the night in the first weeks of life (i.e. in summer), reaching a peak shortly after dusk. Entrainment and drift of benthic species, and of fish older than 0 +, were negligible. Mortality following entrainment was 100%. Impingement of fish on the intake screens was negligible, probably because individuals larger than the screen mesh were able to escape the intake current. The species composition and length-frequencies of the drifting fish, but not their overall abundance, showed some variation with distance from the river margin. It is argued that the fish vulnerable to entrainment are those 0 + individuals which are dispersing in the river by drifting.