Coho Salmon are Behaviourally Resilient After 120 Days of Rearing Under Altered Photoperiods and Salinities
Recirculating aquaculture systems (RAS) are a sustainable method used in aquaculture to farm healthy stocks of fish intended for market. In order to optimize fish growth, environmental conditions within RAS, including salinity and photoperiod are manipulated. However, little is known about the effect of varying photoperiod and salinity on behaviour. In this study, Coho salmon (Oncorhynchus kisutch) smolts were reared in RAS for 120 days on either a 12 hour light: 12h dark or 24 hour light photoperiod and in salinities of either 2.5, 5, or 10 ppt. An additional group reared in 30 ppt and 24h light was examined. To determine the impact of photoperiod and salinity on behaviour, three behavioural test assays were employed. Locomotion was quantified using an open field test, the novel object approach test was used to quantify boldness, and the light/dark test was used to quantify anxiety-like behaviour. In the open field test we observed no significant differences in locomotion. In the novel object approach test, the 2.5 ppt (12h/12h) group demonstrated decreased boldness relative to the 10 ppt (24h) and 30 ppt (24h) groups. In the light/dark test, the 2.5 (12h/12h) group spent significantly less time in the dark zone. However, no significant differences were observed between any of the treatment groups, suggesting that anxiety-like behaviour was only minimally impacted. Taken together, the photoperiods and salinities investigated did not significantly affect coho salmon behaviour, which has important implications for RAS aquaculture.
Presented in absentia on April 27, 2020 at "Student Research Day" at MacEwan University in Edmonton, Alberta. (Conference cancelled)
Faculty Mentor: Trevor Hamilton
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