Institute of Fishing Resources Varna, 4 Primorski, 9000 Varna, Bulgaria
Abstract. Overfishing in the World Ocean including the Black Sea, as well as the global pollution led to a reduction in the quantity of industrial fish species. The occurring changes have led to the focus of fishing organizations and companies to catch some non-fish resources of economic importance. The catches help meet both the domestic market needs and increase the export list of some other marine resources. The main subject of the study are the mollusk populations of species such as black mussels (Mytilus galloprovincialis) and Rapana venosa used economically, the species form aggregations and could be subject to potential catch. The paper summarizes the results from the studies of these species in order to track the changes of their biological characteristics and to take measures for catch methods and control by the competent authorities.