Abstract
Husbandry procedures, albeit essential for good welfare, can be stressful for captive individuals. Therefore, being aware of the physiological effects of these procedures and reducing stress during regular maintenance is of pivotal importance to ensure outstanding welfare. Environmental enrichment can be an asset to animal keepers since it has many benefits on captive animals, including reducing stress in many aquatic species. We studied whether structural enrichment had a positive effect on brood-stock gilthead seabream (Sparus aurata) during four husbandry procedures. We studied the stress levels of the subjects by measuring their heart rate with an internal bio-logger (DST milli HRT, Star-Oddi) surgically implanted in 18 fish. These fish were distributed in six 3000 L cylindrical tanks, and housed with seven more fish in the tanks, which made a total of 10 fish per tank. Three of the tanks had an environmental enrichment structure consisting of a 1 m2 floating structure with 9 hanging organic ropes, while the other three tanks had no enrichment. Fish were exposed to their housing setting for five months. After this environmentally enriched/bare period, we carried out feeding, netting, and cleaning each day for three consecutive days, and a formaldehyde bath on the fourth day in logger-implanted fish, and continued recording their recovery for eight more days. We expect the husbandry procedures to evoke a stress response in all the subjects by increasing their heart rate, and the fish housed in enriched environments to have a reduced heart rate and to recover faster from the stressors compared to the fish housed in bare tanks.
Author Contributions
Conceptualization, M.J.C.-Á., F.S., P.A.-L. and J.L.S.; methodology, M.J.C.-Á., A.R.O. and A.C.-M.; software, M.J.C.-Á.; validation, M.J.C.-Á.; formal analysis, M.J.C.-Á.; investigation, M.J.C.-Á., P.A.-L. and J.L.S.; resources, M.J.C.-Á., P.A.-L. and J.L.S.; data curation, M.J.C.-Á.; writing—original draft preparation, M.J.C.-Á.; writing—review and editing, M.J.C.-Á., A.R.O., P.A.-L. and J.L.S.; visualization, M.J.C.-Á.; supervision, F.S., P.A.-L. and J.L.S.; project administration, F.S., P.A.-L. and J.L.S.; funding acquisition, F.S., P.A.-L. and J.L.S. All authors have read and agreed to the published version of the manuscript.
Funding
This study received Portuguese national funds from the FCT-Foundation for Science and Technology through project UIDB/04326/2020 and doctorate grant UI/BD/151304/2021, and DIVERSIAQUA II (MAR-02.01.01-FEAMP-0175).
Institutional Review Board Statement
The experiment complied with the Guidelines of the European Union Council (Directive 2010/63/EU) and Portuguese legislation for the use of laboratory animals, and was conducted at Centre of Marine Sciences (CCMAR) facilities (Faro, Portugal). CCMAR facilities and their staff are certified to house and conduct experiments with live animals (Group-C licences by the Direção Geral de Alimentação e Veterinária, Ministério da Agricultura, Florestas e Desenvolvimento Rural, Portugal).
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Conflicts of Interest
The authors declare no conflict of interest.
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. |
© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).