Downstream migration: Problems and facilities

This paper, which is an update of chapter 13 of the N degrees 326-327 of th e Bulletin Francais de la Peche et de la Pisciculture by the same authors, deals with downstream migration problems, namely fish damage in spillways a nd hydraulic turbines and design of fish devices which are used to prevent entry of downstream migrants into intakes. Various operational or promising techniques (screening and other behavioural diversion barriers) are presen ted. They are mainly related to migratory salmonids for which a lot of expe riments have been conducted. The authors focus on the design and use of sur face bypasses installed near intake bar racks which are the most promising devices for small hydroelectrical plants in France. Problems related to oth er migratory species are presented.