Studies on the Behavior of Fish in Relation to Power Station Operation in the U.K.

Abstract

The behavior and movement patterns of fishes in their natural environment may be key factors determining whether an effluent or any other ecological disturbance has a significant effect on the populations. Alterations in migration, dispersal, feeding or breeding movements may, in the long term, cause adverse effects. Since 1973, ultrasonic tracking has been used to study the movements and behavior of freshwater and estuarine fishes in relation to water-use by British electricity generating stations. Three major areas of research are summarized below.

Studies in rivers heated by thermal discharges are evaluating the effects of effluent plumes on the natural homing, movement and aggregation patterns of non-diadromous (coarse) fishes. Residence times in relation to temperature suggest that the strict constraints on discharges suggested by the E.E.C. may not be ecologically necessary. Avoidance behavior has been noted in field studies. At Dinorwic in North Wales, the construction and operation of an 1800 MW pumped storage scheme may affect a lake and small river system which carry migratory salmonids. The rate of migration of these fish is being investigated in relation to patterns of flow and suspended solids. Small automatic bankside recording stations are used to monitor the passage of sonic-tagged fish. Future thermal or tidal-barrage based generation may affect at least one large estuary in Britain. To prevent ingress of migrating salmonids at water intakes and to plan locations of barrage fish passes, the routes which salmon take through an estuary are being investigated using sonic-tracking techniques. The possible ‘thermal barrier’ effects on migration are being studied. Problems in analysis of tracking data are discussed.