This study discusses the importance of delineating market boundaries prior to undertaking demand analysis. The Northern Adriatic Sea is considered a good case study by which to test this approach, given the richness of species landed there and their heterogeneous distribution across the space involved. Three groups of demersal species (whitefish, cephalopods, and crustaceans) are chosen for the study. First, geographical market boundaries are defined for each product (species) using price–price relations between market places. Second, demand is analyzed inside the defined market area through the linear approximation of the inverse almost ideal demand system. Geographical market integration bears several patterns of complete or partial integ...