| Summary: | Atlantic salmon ( Salmo salar ) is Australias largest and most valuable farmedseafood and makes a significant contribution to the rural economy in the state of Tasmania.It is based around transfer from freshwater hatcheries to marine cage farms and, although itaccounts for a small part of global salmon production, it is noteworthy for several reasons.Industry is innovative and has developed many technological solutions. There is also ahighly active research community which has collaborated widely with industry and otherstake holders across ecosystem effects, genetics, health, nutrition, physiology andreproduction. Of particular interest is the relative closeness of Tasmania to the equatorwhich, along with local conditions, means that average water temperatures sometimesapproach the upper thermal limits for salmon production. Historically, high watertemperatures have been advantageous in promoting high growth, the industry is nowmanaging for potential impacts of climate change.With increasing water temperature metabolic rate increases and dissolved oxygen (DO)decreases so that salmon are more likely to experience hypoxic conditions. Salmon havebeen considered hypoxia sensitive, however some Tasmanian salmon are able to regulatetheir metabolic rate and show a level of robustness to their environment. Furthermore,salmon perform optimally over a wide temperature range and maintain high levels of growthperformance outside the optimum temperature range. Protein, lipid and mineral nutritionunder sub-optimum conditions will be discussed. For example, sub-optimum temperatureand DO impacted increased protein and energy requirements. Increasing watertemperatures also influences the interaction between aquaculture operations and theenvironment. Changes in feeds and in husbandry practices such as feeding and stockingregimes will affect the overall nature of the environmental impact, whilst broader ecosystemprocesses (e.g. seasonal nutrient inputs, current regimes, biogenic processes in thesediment and water column) will be influenced by climate change and may in turn affect thesystems capacity of to assimilate nutrients, both at a local and a system wide scale.Whilst limiting environmental conditions test respiratory physiology, adequacy of nutrientsupply and growth, Atlantic salmon have robust physiological systems for maintainingefficient growth.
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