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Feeding behaviour of cultured rainbow trout (Oncorhynchus mykiss)

Heydarnejad, MS 2007 , 'Feeding behaviour of cultured rainbow trout (Oncorhynchus mykiss)', PhD thesis, University of Tasmania.

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The primary aim of this study was to examine feeding behaviour of rainbow trout (Oncorhynchus mykiss), under a scheduled time and place delivery of food, using an integrated approach encompassing fish distribution, feeding anticipatory activity (FAA), and sociality as influenced by the light-dark (LD) cycle and food availability.
Using a freshwater recirculated system in a temperature- and light-controlled insulated room, the rainbow trout were maintained in Rathbun tanks and small raceways under three methods of food delivery (hand-feeding with or without a tube, and tube feeding by means of belt- or demand-feeders) with various stocking densities (n = 8, 20, or 30).
The study was conducted over four long-term (634 days) descriptive experiments with the aid of visual observations and video recordings on VCR and PC systems. The feeding behaviour, distribution and social interactions among the fish in the rearing systems (tanks or raceways), and the ability of the fish to appear at the correct time and place of food delivery (time/place learning) were tested. The results showed that time/place learning is not expressed by all individuals but may be expressed by specific individuals in the group regardless of tank design, feeding method, and/or stocking density used in the experiments. To ascertain and identify which fish were able to demonstrate time/place learning, the fish were tagged individually (n = 8). A dominance hierarchy was observed where the dominant fish controlled the behaviour of the group but unlike the other fish, dominants appeared to show time/place learning. In addition, a correlation between feeding and dominance hierarchies was found whereby the dominant fish consumed a disproportionately larger amount of food than the other fish.
Fish spatial distribution, swimming speed, trigger actuations, and agonistic behaviour were behavioural measures selected as possible indicators of FAA. The study used two, rather than one, meals per day and the appearance of FAA was more likely to be detected using swimming speed and/or the level of agonistic behaviour than the other parameters when testing FAA. The fish are diurnal with most of their feeding confined to the photophase. Feeding activity is strongly anchored to the LD cycle. Periodic food availability appeared to be a weaker zeitgeber than LD. In most cases, the fish are present for the morning meal prior to delivery and appeared to show a preference for this location compared to the afternoon feeding location. The fish feeding activity damped rapidly under food deprivation.

Item Type: Thesis - PhD
Authors/Creators:Heydarnejad, MS
Keywords: Rainbow trout
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Copyright 2006 the author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (PhD)--University of Tasmania, 2007. Includes bibliographical references

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