title: Food anticipatory behaviour as an indicator of stress response and recovery in Atlantic salmon post-smolt after exposure to acute temperature fluctuation.
abstract: In this study we evaluated Pavlovian conditioned food anticipatory behaviour as a potential indicator for stress in groups of Atlantic salmon, and compared this with the physiological stress responses of cortisol excretion into water and hyper-consumption of oxygen. We hypothesised that environmental stress would result in reduced feeding motivation. To assess this, we measured the strength of anticipatory behaviour during a period of flashing light that signalled arrival of food. Further, we expected that fish given a reduced food ration would be less sensitive to environmental stress than fish fed full ration. The fish responded to an acute temperature fluctuation with hyper-consumption of oxygen that decreased in line with the temperature, and elevated cortisol excretion up to 1h after the stressor. These physiological responses did not differ significantly between the food ration groups. The anticipatory behaviour was significantly reduced after the stressor and returned to control levels after 1 to 2 h in the reduced ration group, but not until after 3 to 4 h in the full ration group. Our results show that acute stress can be measured in terms of changes to feeding motivation, and that it is a more sensitive indicator of stress that influences the fish over a longer time period than measures of change in cortisol excretion.
authors.affiliation: Institute of Marine Research, NO-5984 Matredal, Norway. ole.folkedal@imr.no
authors.forename: Ole
authors.initials: O
authors.lastname: Folkedal
authors.forename: Lars H
authors.initials: LH
authors.lastname: Stien
authors.forename: Thomas
authors.initials: T
authors.lastname: Torgersen
authors.forename: Frode
authors.initials: F
authors.lastname: Oppedal
authors.forename: Rolf Erik
authors.initials: RE
authors.lastname: Olsen
authors.forename: Jan Erik
authors.initials: JE
authors.lastname: Fosseidengen
authors.forename: Victoria A
authors.initials: VA
authors.lastname: Braithwaite
authors.forename: Tore S
authors.initials: TS
authors.lastname: Kristiansen
mesh_terms: D000818:Animals; D003214:Conditioning, Classical / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology*; D006854:Hydrocortisone / Q000378:metabolism; D008027:Light; D009042:Motivation / Q000502:physiology*; D010101:Oxygen Consumption; D020317:Salmo salar / Q000502:physiology*; D013312:Stress, Physiological / Q000502:physiology*; D013696:Temperature; D013997:Time Factors; D014741:Video Recording
chemical_list: D006854:Hydrocortisone