Observations of avoidance reactions of migrating salmon to a mobile survey vessel in a riverine environment

Abstract

Detailed avoidance reactions of adult migrating salmon to a mobile survey vessel were successfully observed with side-looking dual-frequency identification sonar (DIDSON) in the lower Fraser River (British Columbia, Canada). Both adult sockeye (Oncorhynchus nerka) and pink salmon (Oncorhynchus gorbuscha) returning to the river were found to avoid the approaching vessel by initiating lateral movements away from the vessel, making the fish unlikely to be insonified by the downward-looking transducers towed by the vessel. The vessel was found to have an estimated mean interference range of 4 m from its propeller. Analyses of the data concluded that once the vessel and fish were separated by more than 7 m, the vessel no longer affected the normal migration behaviour of the fish.Résumé : Un sonar latéral d'identification à double fréquence (DIDSON) nous a permis d'observer avec succès les réac-tions détaillées d'évitement des saumons adultes en migration face à un navire mobile d'inventaire dans le cours inférieur du Fraser (Colombie-Britannique, Canada). Tant les saumons rouges (Oncorhynchus nerka) que les saumons roses (Oncorhynchus gorbuscha) qui retournent dans la rivière évitent le navire qui s'approche en entreprenant des déplacements latér-aux pour se distancer du navire, ce qui fait que les poissons risquent peu d'être repérés par les capteurs sonar orientés vers le bas et tirés par le navire. La portée moyenne de l'interférence du navire est estimée à 4 m depuis l'hélice. Les analyses de ces données mènent à la conclusion que lorsque le navire et les poissons sont séparés par une distance de plus de 7 m, le navire n'affecte plus le comportement normal de migration des poissons.[Traduit par la Rédaction]

Use of high-frequency imaging sonar (DIDSON) to observe fish behaviour towards a surface trawl

“…Split-beam echo-sounders have been successfully used in several occasions to monitor the movements of individual fish (Handegard et al, 2003;Hjellvik et al, 2003;McQuinn and Winger, 2003;Jorgensen et al, 2004;Handegard and Tjostheim, 2005;Rakowitz et al, 2008). In particular, the DIDSON (Dual frequency IDentification SONar) multibeam acoustic camera, which produces near-video images of fish behaviour, has great potential for gear avoidance studies (Handegard and Williams, 2008;Xie et al, 2008). This is especially true in turbid or dark freshwater environments where video or photographic observations fail.…”

An assessment of the size structure, distribution and behaviour of fish populations within a temporarily closed estuary using dual frequency identification sonar (DIDSON)

“…Recently the development and accessibility of high resolution sonar (DIDSON), also called acoustic cameras, has enabled scientists employing this tool to fill the gap between high resolution underwater cameras and standard acoustic echograms (Moursund et al , 2003; Boswell et al , 2008; Xie et al , 2008), especially where low light or turbid conditions prevail. Because of the near video quality visual output, acoustic cameras have the potential to provide data not only on fish abundance, but also on behaviour, a factor recent research suggests may provide insights into fish habitat use patterns within estuaries (Becker et al , 2010).…”

Acoustic assessment of fish resources in subtropical run-off-river hydropower plant in the Pearl River

“…The difference may be interpreted as follows. When the spillways were open during flooding discharge, many fish flushed into the reservoir from the downstream area [15] or passed through the Changzhou Fishway [12,13], Fish are prone to avoid ships, thus leading to the underestimate results [29,30]. In the ship lock of Waijiang, the avoidance reactions of fish lead to the low density.…”