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Does aquaculture diet composition influence the nutrition retention and condition of wild-caught Acanthopagrus butcheri broodstock?

Newton, Jesse Isaiah (2020) Does aquaculture diet composition influence the nutrition retention and condition of wild-caught Acanthopagrus butcheri broodstock? Honours thesis, Murdoch University.

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Abstract

Aquaculture is an essential industry for global food security, with production surpassing that obtained from wild capture fisheries. Future development of this profit- driven industry to meet the needs of a rapid growing population is dependent on the improved efficiency and sustainability of feeding methods. The health and nutrition of broodstock is crucial as it directly influences larval development and survival. Wet diets of whole fish and cephalopods are often fed to broodstock, however, they are abundant in long-chain highly unsaturated fatty acids and high rancidity making them prone to oxidation while in storage. Oxidation makes feed products rancid and degrades reproductive organs in fish, namely the livers. This leads to smaller spawns and reduction in larval survival. Aquaculture production is often limited by poor larval performance as a direct influence of inadequate knowledge of broodstock nutritional requirements. Due to the variance in nutritional requirements at a species level, investigative research is required. Acanthopagrus butcheri, an important recreational fishing species in Australia, fits the criteria for diversification of small-scale aquaculture production outlined by the Food and Agricultural Organisation of the United Nations. This study aims to investigate the impacts of aquaculture diets on the physiological health of wild caught A. butcheri broodstock, by measuring the transfer of dietary nutrients from the following commercial aquaculture diets, frozen squid and pilchards, Breed-M broodstock conditioning diets and C2, a powdered larval diet combined with gelatine into pellets. Breed-M and C2 provided superior fatty acid profiles and antioxidant defence, while pilchards had high rancidity values which led to oxidation of liver tissue. Livers from wild caught fish reflected the lowest oxidation values, despite also containing minimal levels of antioxidants. Breed-M and C2 provide antioxidants and fatty acids that are excessive of A. butcheri requirements, however wet fish diets of pilchards result in rapid degradation of valuable broodstock, negatively impacting growth and the physiological condition of reproductive organs. This study provides insight into the dietary requirements of finfish broodstock and shows the implications of insufficient broodstock nutrition in aquaculture production.

Item Type: Thesis (Honours)
Murdoch Affiliation: Environmental and Conservation Sciences
United Nations SDGs: Goal 14: Life Below Water
Supervisor(s): Partridge, Gavin, Roennfeldt, Ben, Cottingham, Alan and Tweedley, James
URI: http://researchrepository.murdoch.edu.au/id/eprint/57696
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