Use of Radiotracking in France for Recent Studies Concerning the E.D.F. Fishways Program

Abstract

Radiotracking studies have been carried out since 1985 on three species of migratory fish - Atlantic salmon (Salmo salar , sea trout (Salmo trutta trutta) , shad (Alosa alosa) - in relation to surveys carried out before and after the construction of fishways on Electricite de France dams. Three sites were investigated: — Poutes-Monistrol hydropower project on the Allier river: determination of the possibility for Salmon to reach the new fishlift entry located at the Poutes dam; the effect of Monistrol powerhouse discharge on migration was particularly analysed, — st-Laurent-des-eaux weir on the Loire river: determination of the projected fishway's characteristics for shad, — Mauzac.dam on the Dordogne river: determination of the attractivity, for shad and sea trout, of a new fishway located close to the powerhouse. American radiotracking equipment was used (Advanced Telemetry System and Smith Root) with frequency ranges 40-41 MHz and 48-49 MHz. Fishes were tagged with transmitters of various sizes implanted in the stomach. A total of 28 shad, 43 salmon and 18 sea trout were tagged. Various techniques of tracking have been employed according to each site and fish species: — for manual tracking (by foot, car, boat or plane), we employed various antennas: loop, adcock, whip or underwater. Precise location was made by biangulation or trian-gulation with receivers or by use of underwater antennas; — automatic tracking with graphic recorders was used for continuous observations.Transports upstream by truck have been tested. They give good results only under specifc conditions. The duration of studies varied from 2 months to 8 months. The accuracy of results is directly dependent on the number of personnel assigned to the study. Use of radiotracking to survey or to design fishways appears to be a lumbersome but irreplaceable technique for the obtention of results concerning fish behaviour.