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Effects of simple shelters on growth performance and welfare of rainbow trout juveniles

Gesto, Manuel and Jokumsen, Alfred (2022) Effects of simple shelters on growth performance and welfare of rainbow trout juveniles. [Effekter af simple skjul på vækst og velfærd hos regnbueørred sættefisk.] Aquaculture, 1, pp. 1-12.

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Summary

Environmental enrichment is a promising strategy to improve the welfare of fish in captivity. However, the utilization of enrichment in aquaculture is still infrequent, maybe because there is a paucity of knowledge about how its effects depend on factors such as fish species, developmental stage, social environment or the type and extent of enrichment. In this study, we evaluated the effects of physical enrichment on the welfare of rainbow trout juveniles, by exposing them to simple plastic screen shelters. Juveniles of approx. 15 g were introduced to two types of submerged shelters: full screens (Full) or partial screens (Semi), and fish welfare was assessed by evaluating fish growth and condition, extent of external lesions, and the neuroendocrine responses to acute and repeated stress. During the eleven-week experimental period, the fish in the sheltered units gradually developed a clear shelter-seeking behavior when exposed to external disturbance. Fish growth, condition factor and mortality were not affected by shelter presence. The presence of full shelters had a modest protective effect on fin damage: both pectoral fin- and total fin scores were reduced (> 10%) in this group with respect to the control group. The presence of shelters did not affect the general level of stress upon standardized acute or repeated stressors. However, fish used to the presence of shelters showed a more intense startling response when exposed to stressors that forced them to abandon the shelter protection. Altogether, this study shows potential for shelters to be used as a welfare-promoting strategy in trout farming, but further research is needed to optimize the shelter type and design and the proper timing for its application.


Summary translation

Etablering af “Strukturelt berigede miljøer” er en lovende strategi til forbedring af velfærden for fisk i akvakultur. Men hvordan hænger evt. effekter heraf sammen med faktorer som fiske art, udviklingsstadie, type skjul mm? I dette studie undersøgte vi effekter af skjul på velfærd hos regnbueørred sættefisk ved at udsætte dem for simple plastik skjul. På sættefisk på ca. 15 g blev testet to typer dykkede skjul: fuld skjul (Fuld) og delvist skjul (Semi), og fiskevelfærd blev bedømt ud fra fiske vækst og kondition, ydre læsioner samt neuroendocrine responser på akut og gentagen stress. Under den elleve uger forsøgs periode udviste fisk med skjul en adfærd mod skjul ved ydre forstyrrelser. Fiske vækst, konditions faktor og dødelighed var ikke påvirket af skjul. Fuld skjul havde en moderat beskyttende effekt på finne skader: både brystfinne og total finne score blev reduceret (> 10%) i denne gruppe i forhold til kontrol. Skjul havde ikke nogen særlig betydning for stress niveau i forhold til standardiseret akut eller gentagen stress påvirkning. Men fisk tilvænnet skjul udviste en kraftigere respons, når de blev udsat for stress påvirkning, som tvang dem væk fra skjul beskyttelsen. Studiet viste potentiale for at anvende skjul til fremme af velfærd hos regnbueørred i akvakultur, men mere forskning må vise frem mod optimering af type skjul og design samt rette timing for dets anvendelse.

EPrint Type:Journal paper
Keywords:Welfare, environmental enrichment, stress, trout shelter
Agrovoc keywords:
Language
Value
URI
English
UNSPECIFIED
UNSPECIFIED
Subjects: Animal husbandry > Health and welfare
Research affiliation: Denmark > Organic RDD 4 > ShelterFish
DOI:10.1016/j.aquaculture.2022.737930
Deposited By: Jokumsen, Senior Advisory Scientist Alfred
ID Code:42568
Deposited On:09 Dec 2021 09:04
Last Modified:26 Jan 2022 08:37
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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