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Author

Niall Bromage

Other affiliations: Aston University
Bio: Niall Bromage is an academic researcher from University of Stirling. The author has contributed to research in topics: Rainbow trout & Trout. The author has an hindex of 57, co-authored 136 publications receiving 8906 citations. Previous affiliations of Niall Bromage include Aston University.
Topics: Rainbow trout, Trout, Broodstock, Sea bass, Melatonin


Papers
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Journal ArticleDOI
TL;DR: There is increasing public, governmental and commercial interest in the welfare of intensively farmed fish and stocking density has been highlighted as an area of particular concern, and there are contradictory recommendations in the literature for key water quality parameters to ensure adequate welfare status.
Abstract: There is increasing public, governmental and commercial interest in the welfare of intensively farmed fish and stocking density has been highlighted as an area of particular concern. Here we draw scientific attention and debate to this emerging research field by reviewing the evidence for effects of density on rainbow trout. Although no explicit reference to ‘welfare’ has been made, there are 43 studies which have examined the effects of density on production and physiological parameters of rainbow trout. Increasing stocking density does not appear to cause prolonged crowding stress in rainbow trout. However, commonly reported effects of increasing density are reductions in food conversion efficiency, nutritional condition and growth, and an increase in fin erosion. Such changes are indicative of a reduced welfare status—although the magnitude of the effects has tended to be dependent upon study-specific conditions. Systematic observations on large scale commercial farms are therefore required, rather than extrapolation of these mainly small-scale experimental findings. There is dispute as to the cause of the observed effects of increasing density, with water quality deterioration and/or an increase in aggressive behaviour being variously proposed. Both causes can theoretically generate the observed effects of increasing density, and the relative contribution of the two causes may depend upon the specific conditions. However, documentation of the relationship between density and the effects of aggressive behaviour at relevant commercial densities is lacking. Consequently only inferential evidence exists that aggressive behaviour generates the observed effects of increasing density, whereas there is direct experimental evidence that water quality degradation is responsible. Nevertheless, there are contradictory recommendations in the literature for key water quality parameters to ensure adequate welfare status. The potential for welfare to be detrimentally affected by non-aggressive behavioural interactions (abrasion, collision, obstruction) and low densities (due to excessive aggressive behaviour and a poor feeding response) have been largely overlooked. Legislation directly limiting stocking density is likely to be unworkable, and a more practical option might be to prescribe acceptable levels of water quality, health, nutritional condition and behavioural indicators.

603 citations

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TL;DR: Examination of factors that can critically affect fecundity, egg production, egg quality, spawning time, and maintenance of egg supplies examines aspects of brookstock management central to determining total number of eggs produced, quality of eggs, and timing of maturation and spawning.

416 citations

Journal ArticleDOI
TL;DR: The evidence for stronger dominance hierarchies in the 10 kg m − 3 treatment, indicate that low as well as high stocking densities have the potential to adversely affect trout welfare.

292 citations

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TL;DR: Replicate groups of halibut larvae were fed to d 71 post-first feeding either the marine copepod, Eurytemora velox, or Artemia nauplii doubly enriched with the marine chromist or golden algae, Schizochytrium sp.
Abstract: Replicate groups of halibut larvae were fed to d 71 post-first feeding (PFF) either the marine copepod, Eurytemora velox, or Artemia nauplii doubly enriched with the marine chromist or golden algae, Schizochytrium sp., (Algamac 2000) and a commercial oil emulsion (SuperSelco). The fatty acid compositions of eyes, brains and livers from larvae fed the two diets were measured, and indices of growth, eye migration and skin pigmentation were recorded along with histological examinations of eye and liver. The docosahexaenoic acid [22:6(n-3); DHA]/eicosapentaenoic acid [20:5(n-3); EPA] ratios in Artemia nauplii enriched with the SuperSelco and Algamac 2000 were 0.4 and 1.0, respectively. The E. velox copepods were divided into two size ranges (125-250 and 250-400 microm) with the smaller size range containing the highest level of (n-3) highly unsaturated fatty acids (HUFA). The DHA/EPA ratios for the two size ranges of copepods were 2.0 and 0.9, respectively. The total lipids of eyes, brains and livers of larvae fed copepods had higher levels of DHA and lower levels of EPA than those of larvae fed enriched Artemia. The percentage of survival of the halibut larvae was significantly higher when copepods rather than enriched Artemia nauplii were fed, but larval specific growth rates did not differ. The indices of eye migration were high and not significantly different in larvae fed the two diets, but the percentage of larvae undergoing successful metamorphosis (complete eye migration and dorsal pigmentation) was higher in larvae fed copepods (40%) than in larvae fed enriched Artemia (4%). The rod/cone ratios in histological sections of the retina were 2.5 +/- 0.7 in larvae fed copepods and 1.3 +/- 0.6 in larvae fed enriched Artemia (P < 0.01). Histological examination of the livers and intestines of the larvae were consistent with better assimilation of lipid from copepods than lipid from Artemia nauplii up to 46 d post-first feeding. Thus, marine copepods are superior to enriched Artemia as food for halibut larvae in terms of survival, eye development and pigmentation, and this superiority can be related to the level of DHA in the feed.

276 citations


Cited by
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TL;DR: The lability of sex-determination systems in fish makes some species sensitive to environmental pollutants capable of mimicking or disrupting sex hormone actions, and such observations provide important insight into potential impacts from endocrine disruptors, and can provide useful monitoring tools for impacts on aquatic environments.

2,283 citations

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TL;DR: Exposure of male rainbow trout to four different alkylphenolic chemicals caused synthesis of vitellogenin, a process normally dependent on endogenous estrogens, and a concomitant inhibition of testicular growth, support the contention that exposure of wildlife to environmentally persistent estrogenic chemicals can result in deleterious reproductive consequences.
Abstract: It is becoming evident that an increasing number of widely used industrial and agricultural chemicals are estrogenic. The biodegradation products of a major group of nonionic surfactants, the alkylphenol polyethoxylates, are one such group. Some of these chemicals are widespread aquatic pollutants, and bioconcentrate in aquatic biota. Exposure of male rainbow trout (Oncorhynchus mykiss) to four different alkylphenolic chemicals caused synthesis of vitellogenin, a process normally dependent on endogenous estrogens, and a concomitant inhibition of testicular growth. The magnitude of these estrogenic effects was dependent on the estrogenic potency of the chemical, the stage of reproductive development of the fish, and the concentration of the chemical in the water. These results support the contention that exposure of wildlife to environmentally persistent estrogenic chemicals can result in deleterious reproductive consequences.

1,245 citations

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TL;DR: It is deduced that differences in essential fatty acid requirements for different species of fish reflect different dietary and metabolic adaptations to different habitats and how such knowledge can be exploited to develop improved diets for fish, especially in their early stages of development.

1,033 citations

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TL;DR: Simultaneous exposure of the hepatocytes to Tamoxifen and effective doses of representative compounds caused an inhibition of the oestrogenic effect in all cases, suggesting that the action of these compounds is mediated by the Oestradiol receptor.

1,029 citations

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TL;DR: An improvement in broodstock nutrition and feeding has been shown to greatly improve not only egg and sperm quality but also seed production, and protein component of cuttlefish and squid together with their optimal concentration of HUFA appear to be responsible for their positive effect on reproductive performance.

961 citations