REVIEW ARTICLE Towards effective nutritional management of waste outputs in aquaculture, with particular reference to salmonid aquaculture operations Dominique P Bureau & Katheline Hua UG/OMNR Fish Nutrition Research Laboratory, Department of Animal and Poultry Science, University of Guelph, Guelph, ON, Canada Correspondence: D P Bureau, UG/OMNR Fish Nutrition Research Laboratory, Department of Animal and Poultry Science, University of Guelph, Guelph, ON, Canada N1G 2W1. E-mail: dbureau@uoguelph.ca Abstract Long-term sustainability of many ¢sh culture opera- tions may be dependent on their ability to reduce their waste outputs. The release of solid wastes is mainly a function of the digestibility of various diet- ary components, and the release of dissolved wastes is mainly a function of the metabolism of nutrients by the ¢sh. Consequently, simple principles of nutrition and models have been e¡ectively used to describe, predict and manage the excretion of wastes by ¢sh. Nutritional strategies o¡er a direct and e¡ective way of managing waste output by aquaculture opera- tions.Very signi¢cant reduction in waste outputs per unit of ¢sh produced, notably in terms for solid and phosphorus wastes, have been achieved over the past few decades by commercial ¢sh culture operations. Further reduction in waste outputs could be achieved through ¢ne-tuning of feed formulations, judicious use of feed additives and processing/re¢n- ing of ingredients. A better understanding of the ba- sis of the e¡ect of various endogenous (biological) and exogenous (dietary, environmental) factors on nutrient utilization by ¢sh could also contribute to the development of strategies for reducing waste out- puts. The present paper provides a brief overview of issues and challenges related to potential environ- mental impacts of wastes, and of recent progresses relative to nutritional strategies aimed at better man- agement of the release of wastes by aquaculture op- erations. Keywords: aquaculture, ¢sh, feed, environment, waste, pollution Introduction The environmental impact of ¢sh culture operations is becoming a matter of close scrutiny in many parts of the world. The release of wastes by aquaculture op- erations may result in nutrient enrichment of the re- ceiving environment, which, in turn, may result in environmental changes. Long-term sustainability of many ¢sh culture operations may, therefore, be re- lated to how e¡ectively these enterprises can manage their release of wastes. The e¡ective and meaningful management of waste outputs is a complex issue that can, in broad terms, be simpli¢ed to the management of the release of solid wastes (SW) (mainly organic wastes) and that of ‘elemental’wastes [e.g. nitrogenous or phosphorus (P) containing compounds] in forms that may stimu- late primary productivity (algae and plant) and eu- trophication processes in the receiving water body. Because most of the wastes released by aquaculture operations are ultimately from biological and dietary origins, reduction of waste outputs can be achieved through improvement of the cultured animals them- selves (e.g. through genetic improvements), or im- provement of the feeds and feeding strategies. The paper provides a brief overview of issues and chal- Aquaculture Research, 2010, 41 , 777^792 doi: 10.1111/j.1365-2109.2009.02431.x r 2010 The Authors Journal Compilation r 2010 Blackwell Publishing Ltd 777