A procedure is proposed by which recruit numbers and parental biomass of shrimps stocks can be derived, given a series of catch per effort data and estimates of a few ancillary variables. In the Gulf of Thailand, shrimp recruitment decreased with decreasing egg production, but increased with decreasing total (mainly fish) standing stock. The net result of these counteracting effects was an overall increase in shrimp recruitment, attributable to a greatly reduced prerecruit mortality.