A Boundary Setting Algorithm (BSA) is developed that utilises migration rates estimated by the program BayesAss. It is subjected to preliminary testing through application of the BSA to a subset of TOSSM datasets from Archetypes I and II. Two Fully Internally Mixed Areas (FIMAs) are considered, connected by varying rates of migration. The objective of the BSA, implemented through the run.tossm control program, is to decide whether to manage FIMAs as one or two units. Performance is assessed using the depletion and catch statistics produced by run.tossm. Although BayesAss has the potential to provide information relevant to management, performance of the BSA was found to be poor, apparently due to inconsistent and unreliable estimation of the migration rate