In 2010, the Northeast groundfish fishery transitioned from an effort-control system (Days-at-Sea) to an output-control system (catch shares). Simultaneously, a large decrease in aggregate catch was imposed in order to achieve biological objectives. This research examines the welfare effects of the transition to catch-share management by combining an inverse demand model for groundfish with a simulation based model of supply. The Generalized Differential Inverse Demand System is estimated for groundfish and imports using monthly data from 1994-2011 using a Generalized Method of Moments estimator. The estimated parameters are combined with simulated landings derived from a counterfactual policy scenario had ef- fort controls been retained instead of the catch share system. The simultaneous management change to catch shares and reduction in aggregate catch reduced consumer welfare by approximately $11M. A counterfactual policy in which the Days-at-Sea system was adjusted to meet the catch reductions would have reduced consumer welfare by approximately $37M; this finding is robust to instrument choice in the demand model. Because the 2010 fishing regulations and the counterfactual regulations were designed with the same conservation goals, the difference, approximately $26M, can be attributed to the change in management institution. Finally, reversion to the Days-at-Sea regulatory structure would reduce consumer welfare by approximately $25M from the current (2010) levels.