Spatial distribution and activity patterns as welfare indicators in response to water quality changes in European sea bass, Dicentrarchus labrax

Type Article
Date 2020-05
Language English
Author(s) Alfonso Sebastien1, 2, Sadoul Bastien2, 3, Cousin XavierORCID2, 4, Bégout Marie-LaureORCID1, 2
Affiliation(s) 1 : Ifremer, Laboratoire Ressources Halieutiques, Station de La Rochelle, Place Gaby Coll, 17137 L'Houmeau, France
2 : MARBEC, Univ. Montpellier, CNRS, IRD, Ifremer, 34250 Palavas-les-flots, France
3 : INRAE, UR1037 Fish physiology and Genomics, 35000 Rennes, France
4 : Université Paris-Saclay, AgroParisTech, INRAE, GABI, 78350 Jouy-en-Josas, France
Source Applied Animal Behaviour Science (0168-1591) (Elsevier BV), 2020-05 , Vol. 226 , P. 104974 (11p.)
DOI 10.1016/j.applanim.2020.104974
WOS© Times Cited 21
Keyword(s) Fish, Welfare, Water quality, Behaviour, Stress

In aquaculture, fish are exposed to unavoidable stressors that can be detrimental for their health and welfare. However, welfare in farmed fish can be difficult to assess, and, so far, no standardized test has been universally accepted as a welfare indicator. This work contributes to the establishment of behavioural welfare indicators in a marine teleost in response to different water quality acute stressors. Groups of ten fish were exposed to high Total Ammonia Nitrogen concentration (High TAN, 18 mg.L-1), Hyperoxia (200 % O2 saturation), Hypoxia (20 % O2 saturation), or control water quality (100% O2 saturation and TAN < 2.5 mg.L-1) over 1 hour. Fish were then transferred in a novel environment for a group behaviour test under the same water quality conditions over 2 hours. Videos were recorded to assess thigmotaxis, activity and group cohesion. After this challenge, plasma cortisol concentration was measured in a subsample, while individual behavioural response was measured in the other fish using novel tank diving test. Prior to this study, the novel tank diving test was validated as a behavioural challenge indicative of anxiety state, by using nicotine as anxiolytic drug. Overall, all stress conditions induced a decrease in activity, thigmotaxis and group cohesion while only fish exposed to Hypoxia and High TAN conditions displayed elevated plasma cortisol concentrations. In post-stress condition, activity was still affected but normal behaviour was recovered within the 25 minutes of the test duration. Our work suggests that the activity, thigmotaxis and group cohesion are good behavioural indicators of exposure to degraded water quality, and could be used as standardized measures to assess fish welfare.

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