Aquafin CRC Project 1B5: Feed Technology for Temperate f\Fish Species. Volume 2: Diet Development

World wide, consumption of edible seafood is increasing and by 2025, the world demand for edible seafood is predicted to reach about 140 million tonnes. Capture fisheries are predicted to meet no more than 42% of this demand, with the bulk being met through aquaculture. In fact, world wide aquaculture production has recently achieved parity with wild capture fisheries. The aquaculture of many species, especially the high value carnivorous species most often cultured in the developed world has historically relied on the use of fish meal and fish oil to provide the protein and energy contained in commercial aqua-feeds. These ingredient resources are and will continue to be under considerable pressure and as such they are becoming increasingly expensive. Feed grade ingredients often used in agri-feeds are also being directed into emerging industries such as the bio-fuel sector, further increasing competition and market volatility. Now, more than ever, aquaculture nutrition research is focusing on feed alternatives and ways to improve production efficiencies through a thorough understanding of the nutritional requirements of species. These advances improve the profitability of farms, ensure that consumers have access to high quality, nutritious seafood and that the impacts on the environment are minimised. The research presented in this report has endeavoured to meet the aforementioned challenges as they pertain to the mulloway and yellowtail kingfish industries in NSW and other parts of Australia. In particular, this volume focuses on requirement studies that have increased our knowledge of the digestible protein and energy needs of mulloway and yellowtail kingfish. This volume also provides valuable information on the digestibility of Australian feed ingredients by each species. Together, this work has resulted in the development of a bio-energetic model for both species which will be of great benefit to farmers and feed manufacturers, allowing construction of feeding tables, greater flexibility in feed formulation and the confidence to utilise alternatives to fishmeal in diets for either species. This report also presents separate studies investigating the utilisation of carbohydrates by mulloway and kingfish and the effects of increasing temperature on fish metabolism. In addition, we present two experiments that elucidate the effects of stocking density on the performance of mulloway during the important juvenile stages of growth.