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

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Xie, Yunbo, Michielsens, Catherine G.J., Gray, Andrew P., Martens, Fiona J., Boffey, Jacqueline L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2008
• Subjects: Oncorhynchus gorbuscha; Pink salmon
• Online Access: http://dx.doi.org/10.1139/f08-128; http://www.nrcresearchpress.com/doi/full-xml/10.1139/F08-128; http://www.nrcresearchpress.com/doi/pdf/10.1139/F08-128

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.