The existence of spatial structure in populations of exploited marine fishes challenges our ability to develop reliable stock assessments. Using the northern stock of Black Sea Bass (BSB - Centropristis striata) on the US Atlantic coast as a model species, I will combine empirical and analytical approaches to explore the impacts of the spatial resolution of population and assessment models on the reference points generated by assessments. In this region, the distribution of BSB is highly structured during summer months when the fish are inshore, but the distribution is more widely dispersed when offshore in the winter.