title: Ectoparasitic sea lice (Lepeophtheirus salmonis) affect behavior and brain serotonergic activity in Atlantic salmon (Salmo salar L.): Perspectives on animal welfare.
abstract: Scientific research and public debate on the welfare of animals in human custody is increasing at present. Fish are in this context mentioned with particular attention to the high numbers of individuals reared in aquaculture. Research on fish has also contributed to the understanding of individual variation in the ability to cope with stress and disease. One mediator of such variation is the brain serotonergic (5-hydroxytryptamine, 5-HT) system, which conveys physiological and behavioral responses to stress and sub-optimal rearing conditions. Here we study links between the 5-HT response, melanin-based skin pigmentation, and behavior in laboratory-reared Atlantic salmon (Salmo salar) experimentally infested with ectoparasitic sea lice (Lepeophtheirus salmonis). Lice numbers were more variable in less pigmented fish, while the neurochemical response to ectoparastic lice-increased levels of the main 5-HT catabolite 5-HIAA in the brain stem-did not differ between pigmentation groups. A strong depression of growth and locomotor activity was seen in all infested fish but less pigmented fish grew better than fish with more skin melanization regardless of infestation status. The observed combination of neurochemical and behavioral effects clearly suggest that animal welfare concerns can be added to the list of negative effects of ectoparasitic sea lice.
authors.affiliation: Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Aas, Norway. Electronic address: oyvind.overli@umb.no.
authors.forename: Øyvind
authors.initials: Ø
authors.lastname: Øverli
authors.affiliation: Department of Pharmacology and Toxicology, The Norwegian School of Veterinary Science, Oslo, Norway.
authors.forename: Janicke
authors.initials: J
authors.lastname: Nordgreen
authors.affiliation: Department of Animal Health, National Veterinary Institute, Oslo, Norway.
authors.forename: Cecilie M
authors.initials: CM
authors.lastname: Mejdell
authors.affiliation: Department of Production Animal Clinical Sciences, The Norwegian School of Veterinary Science, Oslo, Norway.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Janczak
authors.affiliation: Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Aas, Norway.
authors.forename: Silje
authors.initials: S
authors.lastname: Kittilsen
authors.affiliation: Department of Biosciences, University of Oslo, Norway.
authors.forename: Ida B
authors.initials: IB
authors.lastname: Johansen
authors.affiliation: Department of Pharmacology and Toxicology, The Norwegian School of Veterinary Science, Oslo, Norway.
authors.forename: Tor E
authors.initials: TE
authors.lastname: Horsberg
mesh_terms: D000704:Analysis of Variance; D000827:Animal Welfare; D000818:Animals; D017756:Aquaculture; D001522:Behavior, Animal / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism* / Q000469:parasitology; D033342:Copepoda / Q000472:pathogenicity*; D008124:Locomotion / Q000502:physiology; D008550:Melatonin / Q000378:metabolism; D020317:Salmo salar / Q000033:anatomy & histology / Q000469:parasitology / Q000502:physiology; D012867:Skin / Q000469:parasitology / Q000473:pathology; D012880:Skin Pigmentation
chemical_list: D008550:Melatonin
keywords: Behavior; Experimental infestation; Neurochemistry; Parasites; Sea lice