The impact of stocking density on the welfare of rainbow trout (Oncorhynchus mykiss)

North, Ben; Turnbull, James; Ellis, Tim; Porter, Mjr; Migaud, Hervé; Bron, James E.; Bromage, Niall

doi:10.1016/j.aquaculture.2006.01.004

Cited by 270 publications

(197 citation statements)

References 52 publications

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“…However, no mortality was observed in any of the selected stocking densities in our current study. Similar results have been reported for farmed fish cultured with good water quality, e.g., rainbow trout, sea bass, red porgy (Pagrus pagrus), African catfish (Clarias gariepinus), and Nile tilapia (Oreochromis niloticus) (Hengsawat et al, 1997;North et al, 2006;Sophie et al 2009;Laizcarrión et al 2012).…”

Section: Discussionsupporting

confidence: 84%

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Tan¹,

Sun²,

Tan³

et al. 2018

Turk. J. Fish. Aquat. Sci.

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We conducted a 71-day experiment to investigate the effects of stocking density in a recirculating aquaculture system (RAS) on the growth performance, body composition, digestive activity, and blood biochemical parameters of the marbled eel Anguilla marmorata. We stocked marbled eel in 1.0 m 3 tanks at stocking densities of 12, 20, and 28 kg/m 3 , which were designated the low-density (LD), medium-density (MD) and high-density (HD) groups. The fish weighed 169.72 ± 2.75 g at the baseline level. Results revealed that the fish in the LD and MD groups had a higher ash content than fish in the HD group. The crude lipid content was significantly lower in the MD and HD groups than in the LD group. The protease activities in the stomach and intestine did not differ among the three groups. The total protein and aspartate aminotransferase levels were higher in the LD group than in the MD group. The alanine aminotransferase level was significantly lower in the LD group. These results indicate that a greater increase resulted in stress and significantly affected the growth of the fish. The optimum stocking density of A. marmorata can be achieved at 20.0 kg/m 3 in a RAS.

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Section: Discussionsupporting

confidence: 84%

Untitled

Tan¹,

Sun²,

Tan³

et al. 2018

Turk. J. Fish. Aquat. Sci.

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“…Maeda et al (2010) also observed a reduction (33.39%) on the final weight of fish with increasing stocking density from 700 to 1000 fish/m³ of fingerlings of O. niloticus and Marengoni (2006) found a decrease of 10.92% in the final weight of tilapia when the density increased from 250 to 400 fish/m³ for 135 days. In this context, the lowest growth of fish, grown under high stocking densities may be due to a simple physical limitation in space or due to physiological stress reactions experienced by fish in poor conditions (North et al, 2006). Stock density of 250 fish/m³ achieved a higher weight gain ( Figure 1A), 66% more than in the other two treatments, and daily weight gain 67% over the other two treatments (Table 3).…”

Section: Resultsmentioning

confidence: 98%

“…In many species, this type of dominance can be reduced by increasing the stock rate as seen in works with rainbow trout (North et al, 2006) and African catfish (Hengsawat et al, 1997). These results can be explained by the hypothesis supported by Ellis et al (2002) that a high density condition does not always result in increased fish stress: territorially, fish can reduce its own competitiveness assuming less injurious threat signals when submitted to great densities in stocking, as aggressive behaviors demand high energy cost and sometimes (depending on density) are ineffective.…”

Section: Resultsmentioning

confidence: 99%

Influence of stocking density on growth performance and welfare of juvenile tilapia ( Oreochromis niloticus ) in cages

Costa

Roubach

Dallago

et al. 2017

Arq. Bras. Med. Vet. Zootec.

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Intensification of tilapia production can cause negative implications on performance and welfare of fishes. Thus, it is essential to determine a correct density for optimal production. This study aimed to evaluate performance and animal welfare of juvenile Nile tilapia with an initial weight average of 30g (± 2.70) reared using three different stocking densities in floating net-cages. Fish were fed three times a day with feed containing 32% crude protein during 74 days. The experimental design was completely randomized with 3 treatments (250 fish/m³, 350 fish/m³ and 450 fish/m³) and 4 replicas. The physicalchemical parameters of water were monitored throughout the experiment. Increase in stocking density caused a decrease in the final weight of fish, weight gain, daily weight gain, standard length and survival, as well as an increase in feed conversion. However, higher densities seem to reduce the effect on weight variation. There was no influence of stocking density on final biomass, blood glucose and serum cortisol concentrations. Therefore, the increase of stocking density compromised development and survival of fish, but did not influence the physiological parameters of stress. Thus, treatment with 250 fish/m³ was shown to be the most suitable for fish performance.

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“…Aliquots of pooled rainbow trout plasma were used as quality controls (QCs) and the intra-and inter-specific assay coefficients of variation were 2.1-3.7 % and 5.5 %, respectively. Cortisol was assayed by radioimmunoassay previously described by Ellis et al (2004) and modified by North et al (2006). Aliquots of pooled rainbow trout plasma were used as quality controls (QCs) and the intraspecific assay coefficients of variation was 4.2 %.…”

Section: Hormonal Assaysmentioning

confidence: 99%

Retinal light input is required to sustain plasma melatonin rhythms in Nile tilapia Oreochromis niloticus niloticus

Martinez-Chavez

Migaud

2009

Brain Research

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The aim of this work was to confirm previous findings suggesting that the eyes are required for night-time melatonin production in Nile tilapia and further characterise this divergent circadian organisation. To do so, melatonin levels were firstly measured in eyecups and plasma to determine circadian patterns of melatonin production.Secondly, the effect of partial ophthalmectomy on the suppression of melatonin production was determined in vivo as well as ex vivo pineal light/dark sensitivity.Finally, to investigate whether such findings could be related to post-surgery stress, melatonin analyses were performed in the subsequent 24 h and 7 days postophthalmectomy with cortisol levels assessed as an indicator of stress. Our results showed an inverse pattern of melatonin production in the eye cups of tilapia compared to blood circulating levels, suggesting different roles played by melatonin in these two tissues. Results then demonstrated that total or partial ophthalmectomy resulted in the suppression of night-time melatonin production. Furthermore, although pineals in culture were shown to be photosensitive, night-time melatonin levels were much lower than seen in other species. Finally, when performing sampling immediately or one week post-surgery, no difference in the melatonin profiles were observed. It is therefore unlikely that post-surgery stress would explain such suppression in melatonin production although all fish displayed high cortisol levels most probably due to social and handling stress. Taken together, these results provide further evidence of a new type of circadian organisation in a teleost species where the eyes are required to sustain night time melatonin levels. Section: Regulatory systems

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The impact of stocking density on the welfare of rainbow trout (Oncorhynchus mykiss)

Cited by 270 publications

References 52 publications

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Influence of stocking density on growth performance and welfare of juvenile tilapia ( Oreochromis niloticus ) in cages

Retinal light input is required to sustain plasma melatonin rhythms in Nile tilapia Oreochromis niloticus niloticus

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