title: Effect of predictability on the stress response to chasing in Atlantic salmon (Salmo salar L.) parr.
abstract: The possibility to prepare for and respond to challenges in a proper manner is essential to cope with a changing environment, and learning allows fish to up or downregulate the stress response based on experience. The regulation of the response to predicted needs should be easier in more predictable environments. We exposed salmon parr to chasing of either 15 s (weak stressor) or 5 min (strong stressor) twice daily for a 7-day learning period, with chasing either announced by a 30 s light signal (conditioned) or not announced (unconditioned). The behavioural response to the light signal was different between the conditioned and unconditioned groups, demonstrating that conditioned groups associated the signal with chasing. We could, however, not demonstrate any effect on the stress response of anticipation. The fish habituated to repeated stress exposures with a similar decrease in oxygen hyperconsumption in all groups. Due to habituation, possible effects of predictable announcement of a stressor on the physiological stress response may not have been expressed in this study. Plasma cortisol concentrations 1h after light signal and chasing the day after the training period was moderate in all groups although higher after 5 min chasing (13 ng ml(-1)) than 15 s chasing (7 ng ml(-1)). There was no physiological stress response after exposure to the light signal only after the learning period. We argue that the benefit of predictability of stressors is limited when the fish have no way to avoid the stressor.
authors.affiliation: Institute of Marine Research, NO, 5984 Matredal, Norway.
authors.forename: Angelico
authors.initials: A
authors.lastname: Madaro
authors.affiliation: Department of Biology, University of Bergen, P.O. Box 7800, 5020 Bergen, Norway.
authors.forename: Anders
authors.initials: A
authors.lastname: Fernö
authors.affiliation: Institute of Marine Research, NO, 5984 Matredal, Norway.
authors.forename: Tore S
authors.initials: TS
authors.lastname: Kristiansen
authors.affiliation: Institute of Marine Research, NO, 5984 Matredal, Norway; Norwegian University of Science and Technology, Department of Biology, 7491 Trondheim, Norway.
authors.forename: Rolf Erik
authors.initials: RE
authors.lastname: Olsen
authors.affiliation: Radboud University, Institute for Water and Wetland Research, Department of Animal Physiology, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands.
authors.forename: Marnix
authors.initials: M
authors.lastname: Gorissen
authors.affiliation: Radboud University, Institute for Water and Wetland Research, Department of Animal Physiology, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands.
authors.forename: Gert
authors.initials: G
authors.lastname: Flik
authors.affiliation: Institute of Marine Research, NO, 5984 Matredal, Norway. Electronic address: jonatan.nilsson@imr.no.
authors.forename: Jonatan
authors.initials: J
authors.lastname: Nilsson
mesh_terms: D000818:Animals; D059031:Anticipation, Psychological / Q000502:physiology*; D001522:Behavior, Animal / Q000502:physiology; D003213:Conditioning, Psychological / Q000502:physiology*; D003463:Cues; D006185:Habituation, Psychophysiologic; D006854:Hydrocortisone / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology; D020317:Salmo salar / Q000502:physiology*; D013312:Stress, Physiological / Q000502:physiology*
chemical_list: D006854:Hydrocortisone
keywords: Allostasis; Conditioning; Habituation; Predictability; Salmon; Stress