Study of returning adult Atlantic salmon on the Gave de Pau river using radiotelemetry

• Main Authors: Chanseau, M., Croze, O., Galiay, E., Larinier, M.
• Other Authors: ENSEEIH TOULOUSE, Partenaires IRSTEA, Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), CSP TOULOUSE, GHAAPPE TOULOUSE, Ressources aquatiques continentales (UR RABX), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), irstea
• Format: Report
• Language: French
• Published: HAL CCSD 1998
• Subjects: CSP; CEMAGREF; GHAAPPE; PYRENNEES ATLANTIQUES; GAVE DE PAU COURS D'EAU; [SDE]Environmental Sciences; Atlantic salmon; Salmo salar
• Online Access: https://hal.inrae.fr/hal-02578490

The behaviour of 21 Atlantic salmons was monitored in 1997 from may to december using radiotelemetry on the Gave de Pau river. This study permited to determine the impact of 15 of the 38 obstacles built on the river. It appeared that 7 obstacles seemed not to delay migration, most of fish being able to pass over within 24 hours. Five obstacles permitted to all fish to pass over within few days and 3 obstacles delayed fish longer time. Three plants seemed to be major obstacles regarding to the percentages of fish that over and the migration delays. The attractivity of several fishpasses (Sapso, Denguin, Heid, Narcastet, Peyrouse et Vizens) should be improved. Some of the auxiliary water (Peyrouse, Vizens or Montaut) and rafts passes located near fishpasses (Denguin or Nacastet) can reduce the fishpass attractivity. Plants with diversion canal (Sapso, Peyrouse and Vizens) increased migration delays. Flows in bypassed sections seemed not to be sufficient to allow rapid passages upstream and to reduce the atttractivity of the tailraces. Results revealed the necessity to make a constant watch over fishpass, some of the migration delays resulting from obstructions of the devices. This experimentation revealed others aspects of upstream migration of salmon : quiescent phase, conditions of passing over the obstacles, mortalities. This study complete those realized in 1995 and 1996 respectively on the lower part and the upper part of the river and allows us to have a general view of the migration difficulties encountered by fish. This 3-year study permitted to define the fishpass amelioration priorities indeed the construction of new devices on the major obstacles. Le comportement de 21 saumons atlantiques (Salmo salar) a été suivi de fin mai à mi-décembre 1997, grâce à la technique de radiopistage, sur l'ensemble de l'axe du Gave de Pau. Cette étude a permis d'apprécier la franchissabilité de 15 aménagements sur les 38 actuellement érigés sur le Gave. Sept ouvrages n'ont présenté aucune difficulté à la migration. Deux ...