Enrichment of Circular Tanks with Vertically Suspended Strings of Colored Balls Improves Rainbow Trout Rearing Performance

Kientz, Jeremy L.; Crank, Kathleen M.; Barnes, Michael E.

doi:10.1002/naaq.10017

Cited by 27 publications

(57 citation statements)

References 39 publications

(51 reference statements)

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“…The suspended structures used in this study greatly improved Rainbow Trout growth and feed conversion ratio, supporting the findings of Kientz and Barnes () and Kientz et al. (). The magnitude of increase in weight gain and feed conversion ratio with the spherical structures was similar to that reported by Kientz et al.…”

Section: Discussionsupporting

confidence: 89%

“…Four treatments were used in this study: no tank enrichment (control), low‐density spherical enrichment (five strings; illustrated in Kientz et al. ), high‐density spherical enrichment (eight strings; Figure ), and a mix of linear and low‐density spherical structures (Figure ). All tanks were near‐fully covered as described by Walker et al.…”

Section: Methodsmentioning

confidence: 99%

“…), as well as increase fish growth and decrease the feed conversion ratio (Kientz and Barnes ; Kientz et al. ). While environmental enrichment may be beneficial, many hatcheries are hesitant to implement these changes.…”

mentioning

confidence: 99%

“…Kientz et al. () further expanded this technique by observing positive results with the use of five vertically suspended strings of colored spheres. The objective of this study was to expand on the work of Kientz et al.…”

mentioning

confidence: 99%

“…The objective of this study was to expand on the work of Kientz et al. () by increasing the number of spherical structures suspended in rearing tanks and also combining both spherical and rod structures, and observing any potential effects on fish growth or feed conversion ratio.…”

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confidence: 99%

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An Evaluation of Vertically Suspended Environmental Enrichment Structures during Rainbow Trout Rearing

2018

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Environmental enrichment is the addition of substrate or structural complexity to typically sterile culture environments, but the effects of enrichment on fish rearing performance are relatively unknown. This 127‐d study examined the growth and condition of juvenile Rainbow Trout Oncorhynchus mykiss reared in near‐fully covered circular tanks (1.8 m diameter) with three novel environmental treatments: (1) eight vertically suspended nylon strings with seven colored (6.4 cm diameter) plastic spheres (high density), (2) five vertically suspended strings with seven colored plastic spheres (low density), and (3) a mixture of five vertically suspended colored plastic spheres and nine vertically suspended aluminum rods. Near‐fully covered tanks without enrichment were used as a control. Weight gain, feed conversion ratio, individual fish length, and fish weight were significantly improved in environmentally enriched tanks compared with those features in the unenriched control. Among all of the treatments, the tanks of fish with high‐density spheres had significantly higher ending tank weights (i.e., total weight of fish in tank) and weight gain, both of which were nearly 65% and 75% greater, respectively, than in the control tanks. However, high density spheres also interfered with the self‐cleaning nature of the circular tanks. No significant differences in splenosomatic indices, viscerosomatic indices, hepatosomatic indices, and relative fin lengths were observed among the three enrichment treatments. Based on the results of this study, the use of either low‐density spheres or a mix of rods and spheres is recommended during the rearing of juvenile Rainbow Trout in circular tanks.

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Section: Discussionsupporting

confidence: 89%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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An Evaluation of Vertically Suspended Environmental Enrichment Structures during Rainbow Trout Rearing

2018

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Environmental enrichment improves growth and fillet quality in rainbow trout

De la Llave‐Propín,

Martínez Villalba,

Villarroel

et al. 2024

J Sci Food Agric

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BACKGROUNDSome environmental enrichment (EE) methods, such as occupational enrichment (OE), can improve fish growth, but little is known about its effects on fillet quality. In this study, we evaluated the effects of OE using underwater currents, on different aspects of fillet quality and muscle metabolism in rainbow trout (Oncorhynchus mykiss), before and after a handling procedure (fasting). The trout were placed in groups of 30 in separate tanks in three treatments for 30 days: no artificial currents (CON), randomly fired underwater currents (RFC), and continuous underwater currents (CUC). Additionally, half of the individuals in each treatment were fasted (5 days, 45.2 °C days).RESULTSSlaughter weight, condition factor and relative growth were lower in CON fish, indicating a positive effect of OE on growth. Rigor mortis, muscle pH and muscle glycogen levels were similar among treatments, indicating no effect of OE on classical measures of fillet quality. However, significant differences were found regarding fillet colour and muscle enzymes. The fillets of RFC fish were more salmon‐pink in colour, which is favoured by consumers. Also, activity levels of pyruvate kinase and glycogen phosphorylase in muscle were significantly higher in CUC fish, probably due to increased energy demands as pumps were on continually in that treatment.CONCLUSIONOverall, RFC fish seemed to have received enough stimulation to improve growth while not being excessive in terms of exhausting the animals (avoiding negative effects on muscle metabolism), while OE may have provided a hormetic effect, allowing fish to better adjust to of fasting.This article is protected by copyright. All rights reserved.

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Use of Suspended Plastic Conduit Arrays during Brown Trout and Rainbow Trout Rearing in Circular Tanks

et al. 2018

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Environmental enrichment is the modification of otherwise sterile hatchery rearing units to provide structural complexity. We investigated the use of an array of suspended plastic conduit sections as enrichment in large circular tanks during two experiments. Brown Trout Salmo trutta and Rainbow Trout Oncorhynchus mykiss were reared for 126 and 61 d, respectively, in covered, 3.63‐m‐diameter circular tanks that were either void of any structure or enriched with a suspended array of twenty 0.94‐m‐long sections of plastic conduit. Total tank weight gain and feed conversion ratio were significantly improved for both Brown Trout and Rainbow Trout reared with suspended conduit as enrichment compared to unenriched tanks. Enrichment did not significantly affect individual fish length, weight, or condition factor in either experiment, likely because of small sample sizes. The suspended array did not interfere with tank hydraulic self‐cleaning. Based on the results of this study, the use of vertically suspended enrichment structures in circular tanks is recommended to improve trout rearing efficiencies.

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Enrichment of Circular Tanks with Vertically Suspended Strings of Colored Balls Improves Rainbow Trout Rearing Performance

Cited by 27 publications

References 39 publications

An Evaluation of Vertically Suspended Environmental Enrichment Structures during Rainbow Trout Rearing

An Evaluation of Vertically Suspended Environmental Enrichment Structures during Rainbow Trout Rearing

Environmental enrichment improves growth and fillet quality in rainbow trout

Use of Suspended Plastic Conduit Arrays during Brown Trout and Rainbow Trout Rearing in Circular Tanks

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