The data sources upon which to assess the rock lobster resources of the islands of the Tristan da Cunha group are very limited, with original records against which to check available essentially for the last decade only (Edwards, 2007), so that it is only over this period that data can be used with some confidence. At this stage, these amount to annual catch and CPUE data only, as detailed below. This necessitates that a rather simple model be applied to estimate sustainable yield. Details of this model, and results from its application, are provided below.