As yet no satisfactory sophisticated technique exists for assessing the effects of harvesting on multispecies tropical fisheries. Since these fisheries are so intense, however, the workshop reported here represented an attempt to develop a set of practical stock assessment techniques as well as to promote understanding of multispecies relationships. Focus is on freshwater, estuarial, and marine fisheries in Southeast Asia, although much of the discussion has worldwide applicability. Fifteen papers are presented, covering: the inadequacy of available data for even the simplest assessment techniques; simple assessment models, single-species models, ecological simulation models, and the three-bays ecosystem model; intra as opposed to inter species interactions; comparative fish yields from various tropical ecosystems; coral reef fisheries; tropical demersal fisheries; the relationships among ecosystems, food chains, and yields; sensitivity analysis in fisheries management; patterns of management throughout the world and the realities of contemporary fisheries management in Southeast Asia; and directions for future research. Taken together, the papers strongly indicate the paucity of data, the difficulty of the scientific problems, and the urgency for rapid advances in understanding, leading to recommendations which conclude the proceedings.