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Appetite, metabolism and growth regulation in Atlantic salmon ( Salmo salar L.) exposed to hypoxia at elevated seawater temperature
Author(s) -
Vikeså Vibeke,
Nankervis Leo,
Hevrøy Ernst Morten
Publication year - 2017
Publication title -
aquaculture research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.646
H-Index - 89
eISSN - 1365-2109
pISSN - 1355-557X
DOI - 10.1111/are.13229
Subject(s) - biology , appetite , ghrelin , endocrinology , medicine , salmo , smoltification , hormone , hypoxia (environmental) , salmonidae , oxygen , fishery , chemistry , fish <actinopterygii> , organic chemistry
High temperature combined with low dissolved oxygen ( DO ) is one of the most challenging environmental conditions farmed fish experience; thus, understanding their impact on growth regulation is of relevance to cultured and wild populations. This study examines appetite‐ and growth‐regulating mechanisms in Atlantic salmon postsmolt exposed to either high ( HO ) or low oxygen ( LO ) at a suboptimally high temperature (17°C). Additionally, the effects of high ( HE ) and low ( LE ) dietary energy ( DE ) were examined. After a month of treatment, analyses of hormones, regulating appetite (ghrelin) and growth (growth hormone receptor ghr1 and insulin‐like growth factor IGF ‐1), and free amino acids ( FAA ) were measured pre‐ and postprandially at −4, −2, 0, 2, 4 and 6 h. No preprandial ghrelin peaks were detected despite a significant reduction in feed intake and growth under hypoxia compared to normoxia. LO treatment also had an overall negative effect on survival compared to HO , while nutrient retention efficiency, FCR and plasma FAA concentrations were unaffected ( P > 0.05). Feeding HE diet resulted in increased growth (+17%) and improved FCR (−14%) and energy retention efficiency (+26%) independent of DO . Plasma FAA concentrations were unaffected by LO treatment and DE ( P > 0.05). Growth regulatory gene expressions possibly reflect an overall lower growth at a high temperature overriding the impacts of DO and DE . This study also indicates that optimal adaptation time to environmental conditions and feeding regime is crucial for establishing a regular hormonal appetite signalling that reflects real feeding anticipation in salmon.