This paper examines the generation of resource rent during the transition from an over-exploited to an efficiently managed fishery. A simple theoretical model is used to demonstrate that current industry returns may below or even negative during this adjustment phase. A case in point is the New Zealand commercial fisheries which have recently become subject to a Quota Management System. Three sources of evidence on the level of resource rents generated during the initial years of the Quota Management System are examined and compared. These sources are: annual profitability data; the market price of perpetual quota; and the market price of annual lease quota. The evidence in some cases appears to be contradictory and an attempt is made to resolve or explain such differences. It is concluded that a better understanding of price determination in the quota market is required in order to draw correct inferences about rent generation.