Influences of a dam on Atlantic salmon (Salmo salar) upstream migration in the Couesnon River (Mont Saint Michel Bay) using hydroacoustics

The anthropogenic nature of present-day low energy rivers in western France and implications for current restoration projects

“…So, because "working with the river" is not possible in the short term, restoration projects, and in particular the removal of hydraulic structures, often imply the development of active restoration requiring work to permanently change the channel (Giller, 2005;Wheaton et al, 2008;Jähnig et al, 2010;Kondolf, 2012). The effects of restorations projected on fish migration are promising in Normandy (Martignac et al, 2013), but are also costly (Germaine, 2012). As, it is claimed for the alpine rivers (Comiti, 2012), we should instead give priority to rehabilitation projects that are indispensable and also consider other more sustainable processes for channel management in rural environments (e. g. Kristensen et al, 2012).…”

“…The scientific aspect of river management is the responsibility of the French National Agency for Water and Aquatic Environments (ONEMA), an organization largely derived from the Higher Council on Fishing (CSP) in which experts for whitewater rheophilic and lithophilic species and, among them, migrating fish are mainly represented. This influence is further accentuated in Lower Normandy where brown trout and salmon are economic resources for some rivers that have become national references, such as the Touques (Germaine, 2012), the Sée and the Couesnon (Martignac et al, 2013). Although several technical choices are possible to restore the ecological continuity (demolition, partial opening, fish ladders, improved management of sluice gates), the experts lean toward the most drastic Malavoi and Adam, 2007) often to the detriment of local fishing associations whose main focus is on fish species of calm water.…”

Manual fish length measurement accuracy for adult river fish using an acoustic camera (DIDSON)

“…Their L T ranged from 51.0 to 58.9 cm. The range of the tested size (51 to 67 cm) was chosen to fit as close as possible to the length range of Atlantic salmon Salmo salar L. 1758 (grilse component) target fish in our field-study monitoring survey (Martignac et al, 2013).…”

The use of acoustic cameras in shallow waters: new hydroacoustic tools for monitoring migratory fish population. A review of DIDSON technology

“…Nevertheless, good knowledge of migration behaviour, ecology and biological characteristics of fish present in the monitored river can allow the indirect identification of targets. Thus, length differences (extracted from TS distributions), fish morphology, migration period or position of fish in the water column have been used to distinguish species Burwen et al 1998;Guillard and Colon 2000;Burwen et al 2003;Miller et al 2005;Brehmer et al 2006a;Martignac et al 2013). However, rivers and estuaries can host several species whose sizes and migration periods overlap, which increases the difficulty in using acoustic technology to estimate abundance of each species (Hughes 2012).…”

“…These techniques cannot be used on many rivers due to high turbidity and expensive human and/or material resources. So, despite their limits, notably in species identification, hydroacoustic methods have been increasingly used in fish ecology studies at sea (Kracker 2007), in estuaries (Guillard et al 2004;Grothues and Able 2010;Guillard et al 2012b;Martignac et al 2013;Samedy et al 2013) or in river (Duncan and Kubecka 1996;Hughes 1998), providing more accurate monitoring of migratory fish (Burwen et al 1998;Guillard and Colon 2000;Pfisterer 2002;Taylor and Elison 2010). About ten years ago, a dual-frequency identification acoustic camera, the DIDSON (Sound Metrics Corp., Lake Forest Park, WA, USA) (Belcher et al 2001), appeared, enabling more accurate monitoring of migratory fish due to better species identification.…”