Silver eel downstream migration in fragmented rivers: use of a Bayesian model to track movements triggering and duration
Drouineau, H. ; Bau, F. ; Alric, A. ; Deligne, N. ; Gomes, P. ; Sagnes, P.
Type de document
Article de revue scientifique à comité de lecture
Affiliation de l'auteur
IRSTEA BORDEAUX UR EABX FRA ; IRSTEA BORDEAUX UR EABX FRA ; POLE ECOHYDRAULIQUE ONEMA IRSTEA INP TOULOUSE FRA ; IRSTEA BORDEAUX UR EABX FRA ; POLE ECOHYDRAULIQUE ONEMA IRSTEA INP TOULOUSE FRA ; POLE ECOHYDRAULIQUE ONEMA IRSTEA INP TOULOUSE FRA
Résumé / Abstract
Obstacles in rivers are considered to be one of the main threats to diadromous fish. As a result of the recent collapse of the European eel, the European Commission introduced a Regulation, requiring to reduce all sources of anthropogenic mortality, including those caused by passing through hydropower turbines. Improving knowledge about migration triggers and processes is crucial to assess and mitigate the impact of obstacles. In our study, we tracked 97 tagged silver eels in a fragmented river situated in the Western France (the River Dronne). Using the movement ecology framework, and implementing a Bayesian state-space model, we confirmed the influence of river discharge on migration triggering and the distance travelled by fish. We also demonstrated that, in our studied area, there is a small window of opportunity for migration. Moreover, we found that obstacles have a significant impact on distance travelled. Combined with the small window, this suggests that assessment of obstacles impact on downstream migration should not be limited to quantifying mortality at hydroelectric facilities, but should also consider the delay induced by obstacles, and its effects on escapement. The study also suggests that temporary turbines shutdown may mitigate the impacts of hydropower facilities in rivers with migration process similar to those observed here.
Aquatic Living Resources, vol. 30, num. 5, 19 p.