Eidsmo, Julia Thyra Wood (2022) Effects of shelters on the performance and welfare of rainbow trout fingerlings in an organic farm. [Effekter af skygge på trivsel og velfærd hos yngel af regnbueørred på et økologisk dambrug.] Masters thesis, Technical University of Denmark, Section for Aquaculture (DTU Aqua) . . [Submitted]
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Summary
Physical enrichment in the form of shelters has been proposed as a way of promoting fish welfare in organic aquaculture by providing protection from external disturbances and creating more complex rearing environments. In this study, simply designed shelters were implemented for one month, on an organic rainbow trout farm, in the rearing of fingerling sized rainbow trout. Typical barren rearing tanks were used as controls. The aim of this study was to investigate rainbow trout fingerlings’ preference for shelter, and the behavioral response to farm related stress, as well as the cortisol response and growth performance. Results showed that fingerlings preferred to stay under shelter in a non-stressed situation, however the results were not clear when evaluating the behavioral response to a stressor. This was, to some extent, due to assumptions and technical limitations related to the applied method, that relied on software assisted image analysis, to quantify fish distribution as a measure of behavior. Neither basal or acute cortisol differed between shelter reared and non-shelter reared fingerlings. Furthermore, the results showed that shelter presence had no negative effects on the fish growth-performance, measured by condition factor, FCR, biomass gain, mortality, and external health. The short duration of the experiments is suggested as the main reason for the lack of measurable physiological effects of shelter presence. It is concluded that future trials, designed to study the effects of shelter on rainbow trout welfare, would benefit from longer habituation period prior to stress testing and sampling.
Summary translation
“Fysisk berigelse” i form af skjul/skygge er foreslået som en måde at fremme fiske velfærd i økologisk akvakultur ved at give beskyttelse for ydre forstyrrelser og ved at skabe et mere komplekst opdrætsmiljø.
I dette studie blev et simpelt designet skjul implementeret på et økologisk dambrug ved opdræt af yngel af regnbueørred med tilsvarende enheder uden skjul som kontrol.
Formålet med studiet var at undersøge dels regnbueørred yngels præference for skjul, dels deres adfærdsmæssige respons i relation til stress, ligesom kortisol respons og vækst blev undersøgt.
Resultaterne viste, at ynglen foretrak at opholde sig i skjul i ikke stressede situationer. Dog var resultaterne uklare i forhold til adfærdsmæssig respons overfor stress. Dette beroede I nogen grad på antagelser og tekniske begrænsninger i forhold til metode og software billed analyse til kvantificering af fiskefordeling som et mål for adfærd. Hverken basal eller akut kortisol niveau adskilte sig mellem yngel med/uden skjul.
Endvidere viste resultaterne, at skjul ikke havde negative effekter på vækst udtrykt ved konditions faktor, foderkonvertering (FCR), tilvækst, dødelighed samt ydre sundhed. Eksperimentets korte varighed vurderes at være hoved årsagen til mangel på målbare fysiologiske effekter af skjul. Endvidere konkluderes, at I kommende forsøg bør tilvænnings perioden være længere før stress test og prøvetagning.
| EPrint Type: | Thesis |
|---|---|
| Thesis Type: | Masters |
| Keywords: | Organic rainbow trout, shelter, welfare, stress |
| Agrovoc keywords: | Language Value URI English UNSPECIFIED UNSPECIFIED |
| Subjects: | Animal husbandry > Production systems Animal husbandry > Health and welfare Animal husbandry > Production systems > Aquaculture |
| Research affiliation: | Denmark > Organic RDD 4 > ShelterFish |
| Deposited By: | Jokumsen, Senior Advisory Scientist Alfred |
| ID Code: | 43265 |
| Deposited On: | 20 Jan 2022 14:06 |
| Last Modified: | 20 Jan 2022 14:06 |
| Document Language: | English |
| Status: | Submitted |
| Refereed: | Not peer-reviewed |
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