Physiological responses and welfare implications of rapid hypothermia and immobilisation with high levels of CO2 at two temperatures in Arctic char (Salvelinus alpinus)

Seth, Henrik; Axelsson, Michael; Sundh, Henrik; Sundell, Kristina; Kiessling, Anders; Sandblom, Erik

doi:10.1016/j.aquaculture.2013.04.004

Abstract

Carbon dioxide (CO2) is used for immobilisation of Arctic char (Salvelinus alpinus) prior to slaughter at Swedish aquaculture facilities, and fish are routinely exposed to hypothermia in ice water during transport. Yet, information on stress physiological responses to CO2, temperature extremes and their potential interacting effects is scarce for this cold-water species. Here, blood pressure, heart and ventilation rates and plasma variables including ions, haematocrit, glucose and cortisol were measured in cannulated char during exposure to hypothermia (i.e. a rapid temperature drop from 10 degrees C to 0.25 degrees C); as well as to water nearly saturated with CO2 at 10 degrees C and 0.25 degrees C to test the hypothesis that hypothermia alleviates stress responses during CO2 exposure. While all fish maintained equilibrium during the 30 min hypothermic challenge, blood pressure, heart and ventilation rates decreased and plasma cortisol increased moderately. CO2 exposure at 10 and 0.25 degrees C resulted in aversive behavioural reactions before equilibrium was irrecoverably lost after 184 +/- 14 and 191 +/- 9 s, respectively. The physiological responses to CO2 exposure were largely similar at both temperatures with elevated cortisol levels, reduced heart and ventilation rates and hypotension; although reductions in ventilation amplitude and arterial pulse pressure were significantly more pronounced at 0.25 degrees C. It is concluded that hypothermia alone is a relatively mild stressor in this species, while CO2 exposure elicits pronounced physiological and behavioural stress responses that are not alleviated by hypothermia. (c) 2013 Elsevier B.V. All rights reserved.

Keywords

Blood pressure; Carbon dioxide; Cortisol; Heart rate; Haematology; Ventilation

Published in

Aquaculture
2013, volume: 402, pages: 146-151
Publisher: ELSEVIER SCIENCE BV

SLU Authors

Kiessling, Anders
- Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences

UKÄ Subject classification

Fish and Aquacultural Science
Ecology

Publication identifier

DOI: https://doi.org/10.1016/j.aquaculture.2013.04.004

Permanent link to this page (URI)

https://res.slu.se/id/publ/56052