The increase in commercial fisheries production over the last 50 years has been accompanied by an increase in the level of incidental catch and discarding of a number of speices. Approximately one-quarter of the marine commercial catch destined for human consumption is discarded at sea. This has aroused the concern of a number of groups in society, including environmentalists, humanitarians and fisheries themselves. This paper examines the economic incentives to discard fish as well as the effects of different management policies on these incentives. The concept of an optimal level of discarding of discussed taking into account the externalities that can be created by discarding. Finally, the paper reviews the effectiveness of various measures technical, administrative and economic to reduce the level of discarding. Contents Chapter 1: Introduction; Chapter 2: Bycatch and discarding-an overview of the problem; Definitions and concepts, Bycatch and discards, Target and bycatch species, Size and sex considerations, Other bycatch/discarding, Fate of targeted and incidental catch, Magnitude of discarding, Discards by fishing method and region, Marine mammals, turtles and seabirds, Impacts of discards, Environmental impacts of discarding, Economic impacts of discarding, Chapter summary; Chapter 3: Fisheries Management and the Economic of Discarding; Bycatch and technical interaction in an unregulated fishery, Discarding of commercial species in an unregulated multispecies fishery, Price related highgrading, Capacity related highgrading, Input controls, Limited entry, Minimum landing sizes and minimum mesh sizes, Area and seasonal closures, Restrictions on days at sea and other inputs, Output controls, Trip limits, Aggregate quota, Individual transferable quotas, Chapter summary; Chapter 4: Optimal Discarding and Externalities; Externalities and discarding, Economically optimal levels of discarding, Estimation of the optimal level of discarding, Two species fishery with non-commercial bycatch, Two fisheries with different target species, Discards of juvenile target species and gear selectivity, Chapter summary; Chapter 5: Management Measures to Reduce Discarding; Technical measures, Gear selectivity, Area and seasonal closures, Increased bycatch utilisation, Administrative measure, Quota trading, Fixed quota package, Size specific quotas, Permissible quota over-runs, Recording catch against another s quota, Compulsory landing of all catch, Voluntary surrender of over-quota catch, Economic measures, Taxes and subsidies, Deemed values, Quota substitution, Value based ITQs, Effort reductions, Chapter summary; Chapter 6: Conclusion.