In the Autumn of 1995 the whelk fishery of Carmarthen Bay (Wales, UK) was subjected to a considerable increase in fishing effort which was expected to continue into the 1996 season. However, the predicted "boom" fishery was abruptly halted in February 1996 when the UK authorities imposed a fisheries exclusion zone around the Pembrokeshire coast following the "SEA EMPRESS" oil tanker incident and subsequent oil spillage. This paper outlines the reasons why the whelk fishery had become so important in the previous 11 months since its beginning and goes on to detail the methodology used to calculate and assess compensation for economic losses resulting from the fishery's closure. A model was designed to be applicable to the whole fleet, but adaptable for individuals, reflecting vessel performance, and seasonality in catch rates and vessel activity. The design aimed to maintain the relative position of each vessel within the fleet whilst taking into consideration planned changes for the 1996 fishing season.