1. La migration holobiotique des poissons dans une rivière restaurée en Mayenne.
- Author
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CANU, Pao, LUCAS, Yohann, PIAU, Marie-Laure, and BOILEAU, Nicolas
- Abstract
Movements phenology of holobiotic fishes in a restored river in Mayenne. Movement is an essential component of the life cycle of holobiotic fish between spawning, feeding, refuge and growth areas and helps maintain populations in streams undisturbed by fragmentation. These movements were studied from 2019 to 2023 using a video-counting system integrated into a fish pass on a river where ecological continuity has been restored, the Vicoin, in Mayenne. A total of 954 fishes have been observed belonging to 12 species with a high proportion of individuals not determined (57.5%) mainly due to water turbidity. The movements occur during spring with more than 80% of annual observations concentrated, mostly upstreams (±75% of cases) over the period February to June with a median date between March 29 and May 27 depending on the year. No movements are detected during periods of low flow (summer) unlike autumn when movements are observed, at a lesser magnitude, mostly due to limits of the infraed fish counter and of the fish pass. Using a GLM (General Linear Model) model, flow, temperature and, to a lesser extent, rainfalls and photoperiod are the main factors most influencing the abundance of fish movements. This induces significant interannual variability in both phenology and abundance. The movements observed, which are not exhaustive, are nevertheless unprecedented on a small non-coastal river in western France. The spring migration patterns observed is globally similar with published studies on larger rivers. Monitoring will have to be continued and deepened by RFID (Radio Frequency Identification) technique to better understand the origin and movements of all species and better evaluate, over the entire river, phenological and abundance changes with regard to the expected effects of climate change on a restored watercourse. [ABSTRACT FROM AUTHOR]
- Published
- 2024