Preliminary examination of sounds produced by Pacific salmon (Oncorhynchus spp.) during their fall spawning migration

Abstract

A preliminary description of sounds produced by three species of Pacific salmon was conducted to address the lack of quantified call characteristics in previous studies. Wild Chinook salmon (Oncorhynchus tshawytscha), pink salmon (O. gorbuscha), and coho salmon (O. kisutch) were diverted from a natural spawning migration in the Big Qualicum River located on Vancouver Island, British Columbia, Canada and held in the adjacent hatchery during the 2017 fall migration. Underwater sounds were opportunistically recorded continuously over four week in holding raceways containing Chinook only, coho only, or mixed pink and Chinook salmon, and examined for sounds. All groups produced sounds in three categories based on mechanism: hydrodynamic (surface splash), air movement (miscellaneous and 7 named types), and unknown mechanism (pulse). Pulse, gill-bubble fast repetitive tick air movement sounds, and miscellaneous air movement sounds occurred in all groups and differences in some characteristics of sounds were found between the species groups. Additionally, even though pink salmon were not recorded separately, data suggest they produce a very fast repetitive tick air movement sound more often compared to Chinook salmon. Our results represent the first detailed description of the types and characteristics of sounds produced by wild Pacific salmon.