eCite Digital Repository

Metabolic and functional impacts of hypoxia vary with size in Atlantic salmon


Oldham, T and Nowak, B and Hvas, M and Oppedal, F, Metabolic and functional impacts of hypoxia vary with size in Atlantic salmon, Comparative Biochemistry and Physiology. Part A, 231 pp. 30-38. ISSN 1095-6433 (2019) [Refereed Article]

Copyright Statement

Crown Copyright 2019 Published by Elsevier Inc. All rights reserved.

DOI: doi:10.1016/j.cbpa.2019.01.012


The most capricious environmental variable in aquatic habitats, dissolved O2, is fundamental to the fitness and survival of fish. Using swim tunnel respirometry we test how acute exposure to reduced O2 levels, similar to those commonly encountered by fish in crowded streams and on commercial aquaculture farms, affect metabolic rate and swimming performance in Atlantic salmon of three size classes: 0.2, 1.0 and 3.5 kg. Exposure to 4555% dissolved O2 saturation substantially reduced the aerobic capacity and swimming performance of salmon of all sizes. While hypoxia did not affect standard metabolic rate, it caused a significant decrease in maximum metabolic rate, resulting in reduced absolute and factorial aerobic scope. The most pronounced changes were observed in the smallest fish, where critical swimming speed was reduced from 91 to 70 cm s−1 and absolute aerobic scope dropped by 62% relative to the same measurement in normoxia. In normoxia, absolute critical swimming speed (Ucrit) increased with size, while relative Ucrit, measured inbody lengths−1, was highest in the small fish (3.5) and decreased with larger size (medium = 2.2). Mass specific metabolic rate and cost of transport were inversely related to size, with calculated metabolic scaling exponents of 0.65 for bSMR and 0.78 for bMMR. Metabolic O2 demand increased exponentially with current speed irrespective of fish size (R2 = 0.970.99). This work demonstrates that moderate hypoxia reduces the capacity for activity and locomotion in Atlantic salmon, with smaller salmon most vulnerable to hypoxic conditions. As warm and hypoxic conditions become more prevalent in aquatic environments worldwide, understanding local O2 budgets is critical to maximizing the welfare and survival of farmed and wild salmon.

Item Details

Item Type:Refereed Article
Keywords:Salmo salar, aquaculture, stress, critical swimming speed, oxygen, swim tunnel respirometry, metabolic scaling, cortisol, lactate
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Fisheries sciences
Research Field:Fish physiology and genetics
Objective Division:Animal Production and Animal Primary Products
Objective Group:Fisheries - aquaculture
Objective Field:Aquaculture fin fish (excl. tuna)
UTAS Author:Oldham, T (Mrs Tina Oldham)
UTAS Author:Nowak, B (Professor Barbara Nowak)
ID Code:130536
Year Published:2019
Web of Science® Times Cited:29
Deposited By:Fisheries and Aquaculture
Deposited On:2019-01-31
Last Modified:2020-01-14

Repository Staff Only: item control page